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Introduction: Influenza A virus in swine (IAV-S) is common in the United States commercial swine population and has the potential for zoonotic transmission. Objective: To elucidate influenza shedding the domestic pig population, we evaluated two commercial swine farms in Illinois, United States, for 7 weeks. Farm 1 had a recent IAV-S outbreak. Farm 2 has had IAV-S circulating for several years. Methods: Forty post-weaning pigs on Farm 1 and 51 pigs from Farm 2 were individually monitored and sampled by nasal swabs for 7 weeks. Results: RT-PCR results over time showed most piglets shed in the first 2 weeks post weaning, with 91.2% shedding in week one, and 36.3% in week two. No difference in the number of pigs shedding was found between the two nurseries. Reinfection events did differ between the farms, with 30% of piglets on Farm 1 becoming reinfected, compared to 7.8% on Farm 2. In addition, whole genome sequencing of nasal swab samples from each farm showed identical viruses circulating between the initial infection and the reinfection periods. Sequencing also allowed for nucleic and amino acid mutation analysis in the circulating viruses, as well the identification of a potential reverse zoonosis event. We saw antigenic site mutations arising in some pigs and MxA resistance genes in almost all samples. Conclusion: This study provided information on IAV-S circulation in nurseries to aid producers and veterinarians to screen appropriately for IAV-S, determine the duration of IAV-S shedding, and predict the occurrence of reinfection in the nursery period. [ABSTRACT FROM AUTHOR]

COVID-19 infections have underlined that there can be substantial impacts on health after recovery, including elevated mortality. While such post-infection mortality (PIM) is clearly widespread, we do not yet have any understanding of its evolutionary dynamics. To address this gap, we use an eco-evolutionary model to determine conditions where PIM is evolutionarily favoured. Importantly, from a pathogen perspective, there are two potential 'resources': never-infected susceptibles and previously infected susceptibles (provided some reinfection is possible), and PIM only occurs in the latter. A key insight is that unlike classic virulence (i.e. during-infection mortality, DIM) PIM is neutral and not selected against in the absence of other trade-offs. However, PIM modulates characteristics of endemicity, and may also vary with other pathogen-specific components. If PIM is only correlated with transmission, recovery or DIM, it simply acts to modulate their impacts on the evolutionary outcome. On the other hand, if PIM trades off with the relative susceptibility to reinfection, there are important evolutionary implications that contrast with DIM. We find settings where a susceptibility–mortality trade-off (i.e. an increase in mortality leads to higher relative susceptibility to reinfection) can select against DIM but favour PIM. This provides a potential explanation for the ubiquity of PIM. Overall, our work illustrates that PIM can readily evolve in certain settings and highlights the importance of considering different sources of mortality. [ABSTRACT FROM AUTHOR]

AbstractWe examine an SIRS reaction-diffusion model with local dispersal and spatial heterogeneity to study COVID-19 dynamics. Using the operator semigroup approach, we establish the existence of disease-free equilibrium (DFE) and endemic equilibrium (EE), and derive the basic reproduction number, R0. Simulations show that without dispersal, reinfection and limited medical resources problems can cause a plateau in cases. Dispersal and spatial heterogeneity intensify localised outbreaks, while integrated control strategies (vaccination and treatment) effectively reduce infection numbers and epidemic duration. The possibility of reinfection demonstrates the need for adaptable health measures. These insights can guide optimised control strategies for enhanced public health preparedness. [ABSTRACT FROM AUTHOR]

The aim of this meta‐analysis is to compare the clinical outcomes in patients with and without residual osteomyelitis (ROM) after surgical bone resection for diabetic foot osteomyelitis (DFO). We completed a systematic literature search using PubMed, Scopus, and Embase using keywords DFO, Residual OM (ROM), and positive bone margins. The study outcomes included wound healing, antibiotic duration, amputation, and re‐infection. Five hundred and thirty patients were included in the analysis; 319 had no residual osteomyelitis (NROM), and 211 had ROM. There was not a significant difference in the proportion of wounds that healed 0.6 (p = 0.1, 95% confidence intervals [95% CI] 0.3–1.3). The risk of infection was 2.0 times higher (OR = 2.0, p = 0.02, 95% CI 1.1–3.4), and the risk of amputation was 4.3 times higher (OR = 4.3, p = 0.0001, 95% CI 2.4–7.6) in patients with ROM. Patients with ROM received antibiotics significantly longer. The mean difference was 16.3 days (p = 0.02, 95% CI 11.1–21.1). [ABSTRACT FROM AUTHOR]

Background: Understanding the dynamics of SARS-CoV-2 reinfections is crucial for public health policy, vaccine development, and long-term disease management. However, data on reinfections in the general population remains scarce. Objectives: This study aimed to investigate SARS-CoV-2 antibody dynamics among Austrian blood donors, representing healthy adults, over two years following primary infection and to evaluate the reinfection risk. Methods: 117,895 blood donations were analysed for SARS-CoV-2 total anti-N levels from June 2020 to December 2023. We examined anti-N and anti-S antibody dynamics and in vitro functionality in 230 study participants at five defined times during 24 months, assessing associations with demographics, vaccination status, and reinfection awareness. Results: The seroprevalence of SARS-CoV-2 infection-derived anti-N antibodies increased over time, reaching 90% by February 2023 and remaining at that level since then. According to serological screenings, we found an 88% reinfection rate, which is in contrast to participants' reports indicating a reinfection rate of 59%. Our data further reveal that about 26% of reinfections went completely unnoticed. Antibody dynamics were independent of age, sex, and ABO blood group. Interestingly, individuals with multiple reinfections reported symptoms more frequently during their primary infection. Our results further show that vaccination modestly affected reinfection risk and disease course. Conclusion: SARS-CoV-2 reinfections were uncommon until the end of 2021 but became common with the advent of Omicron. This study highlights the underestimation of reinfection rates in healthy adults and underscores the need for continued surveillance, which is an important support for public health policies and intervention strategies. [ABSTRACT FROM AUTHOR]

We have rapidly gained insights into the presence and function of T lymphocytes in non‐lymphoid tissues, the tissue‐resident memory T (TRM) cells. The central pillar of adaptive immunity has been expanded from classic central memory T cells giving rise to progeny upon reinfection and effector memory cells circulating through the blood and patrolling the tissues to include TRM cells that reside and migrate inside solid organs and tissues. Their development and maintenance have been studied in detail, providing exciting clues on how their unique properties used to fight infections may benefit therapies against solid tumors. We provide an overview of CD8 TRM cells and the properties that make them of interest for vaccination and cancer therapies. [ABSTRACT FROM AUTHOR]

To investigate risk factors for re‐infection and compare the outcomes in people with diabetic foot infections. A retrospective chart review was conducted, and 294 hospitalised patients with moderate to severe diabetic foot infections (DFIs) were analysed for this study. The diagnosis and classification of the severity of infection was based on the International Working Group on the Diabetic Foot (IWGDF) infection guidelines. Skin and soft tissue infections were diagnosed based on clinical observations as per IWGDF classification in addition to ruling out any suspected osteomyelitis (OM) through negative bone culture, MRI or WBC SPECT CT. OM was confirmed by bone culture or histopathology. Clinical outcomes were based on a 12‐month follow‐up period. All dichotomous outcomes were compared using χ2 with an alpha of 0.05. The result of this study shows a 48% rate of re‐infection in people admitted to our hospital with moderate and severe diabetic foot infections (DFI). Patients with osteomyelitis present during the index admission were 2.1 times more likely to experience a re‐infection than patients with soft tissue infection (56.7% vs. 38.0% respectively). In the univariate analysis, risk factors for re‐infection included osteomyelitis, non‐healing wounds, prolonged wound healing, antidepressants and leukocytosis. In the regression analysis, the only risk factor for re‐infection was wounds that were not healed >90 days (HR =2.0, CI: 1.5, 2.7, p = 0.001). Re‐infection is very common in patients with moderate and severe diabetic foot infections. Risk factors include osteomyelitis, non‐healing wound, prolonged wound healing, antidepressants and leukocytosis. [ABSTRACT FROM AUTHOR]

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ABSTRACT Elimination of HCV infection as a public health concern by the end of this decade will require a concerted effort in all target populations, including drug‐users in the inner‐city. Several strategies have been proposed to identify, engage and provide HCV‐infected residents with antiviral therapy and maximise treatment and cure achievement. This study aims to assess the effectiveness of a multidisciplinary approach in delivering HCV treatment to people who inject drugs (PWID) within Vancouver's inner city. We have evaluated a novel approach, the Community Pop‐Up Clinic, for its ability to promote access to care and uptake of HCV therapy, with additional analyses of HCV reinfection and opioid‐related mortality. From January 2021 to August 2023, we evaluated 1968 individuals. 620 (31.5%) were found to carry HCV antibodies and of these, 474 (76.5%) were found to be viremic. Treatment engagement has been secured in 387 (81.6%). 326 (84.2%) have started treatment, 60 in the pre‐treatment phase and 1 died of an overdose in pre‐treatment. Of 326, 302 completed treatments, 18 are currently on treatment and 1 died of an overdose. Of 302 who completed treatment, 286 confirmed as cured (SVR 12), 16 are awaiting SVR 4, 2 had documented virologic relapse and 1 was reinfected. Three patients withdrew from treatment. By mITT, the cure rate is 286/288 (99.3%). We documented 2 overdose deaths over 326 PY. The data presented validates multidisciplinary programs such as ours aimed at treating HCV in inner‐cities and highlights societal benefits that could be achieved including lower overdose death rates. [ABSTRACT FROM AUTHOR]

Chronic active Epstein-Barr virus infection (CAEBV) is a progressive and life-threatening disease characterized by persistent or recurrent EBV activation. It has been reported that, γδ T cells, a type of cytotoxic lymphocyte, play a critical role in restricting EBV. However, the functional status of γδ T cells in pediatric CAEBV patients has not yet been described. In this study, flow cytometry analysis was conducted to explore the cytokine production capacity of γδ T cells in CAEBV patients. A diminished frequency of γδ T cells and decreased expression of cytolytic molecule granzyme B were found in CAEBV patients, suggesting a dysfunction in the immune regulatory function of γδ T cells in this disease. [ABSTRACT FROM AUTHOR]

A significant Omicron wave emerged in China in December 2022. To explore the duration of humoral and cellular response postinfection and the efficacy of hybrid immunity in preventing Omicron reinfection in patients with lung cancer, a total of 447 patients were included in the longitudinal study after the Omicron wave from March 2023 to August 2023. Humoral responses were measured at pre‐Omicron wave, 3 months and 7 months postinfection. The detected severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) specific antibodies including total antibodies, anti‐receptor binding domain (RBD) specific IgG, and neutralizing antibodies against SARS‐CoV‐2 wild type (WT) and BA.4/5 variant. T cell responses against SARS‐CoV‐2 WT and Omicron variant were evaluated in 101 patients by ELISpot at 3 months postinfection. The results showed that Omicron‐infected symptoms were mild, while fatigue (30.2%), shortness of breath (34.0%) and persistent cough (23.6%) were long‐lasting, and vaccines showed efficacy against fever in lung cancer patients. Humoral responses were higher in full or booster vaccinated patients than those unvaccinated (p <.05 for all four antibodies), and the enhanced response persisted for at least 7 months. T cell response to Omicron was higher than WT peptides (21.3 vs. 16.0 SFUs/106 PBMCs, p =.0093). Moreover, 38 (9.74%) patients were reinfected, which had lower antibody responses than non‐reinfected patients (all p <.05), and those patients of unvaccinated at late stage receiving anti‐cancer immunotherapy alone were at high risk of reinfection. Collectively, these data demonstrate the Omicron infection induces a high and durable immune response in vaccinated patients with lung cancer, which protects vaccinated patients from reinfection. [ABSTRACT FROM AUTHOR]

We aimed to understand the temporal dynamics of SARS‐CoV‐2 reinfection risk and assess the impact of inactivated vaccination on the occurrence of reinfection. We investigated the reinfection risk of SARS‐CoV‐2 from November 1, 2022, to February 12, 2023, when China rapidly lifted the zero‐COVID policy. The study subjects were those who were first infected during the zero‐COVID period between January 1, 2020, and October 31, 2022, in Dalian city, China. Among the 1961 previous infections, 126 (6.4%, 95% CI: 5.4, 7.5) were reinfected. The risk of reinfection increased over time since initial infection. Compared with those who did not receive or received one dose of inactivated vaccine, receiving two or three doses was associated with additional protection against reinfection among individuals who were infected with pre‐Omicron more than a year earlier, with the OR ranged from 0.33 (95% CI: 0.03, 1.83) to 0.91 (95% CI: 0.22, 3.27). In contrast, no protective effect from two or three doses of vaccines against reinfection was observed among those who were first infected with Omicron variants within a year. Primary or booster vaccination contributed to limited protection against reinfection or symptomatic reinfection among individuals infected with Omicron SARS‐CoV‐2 within a year. However, a booster dose after 1 year of natural infection may provide additional protection against reinfection. [ABSTRACT FROM AUTHOR]

Immunological priming—in the context of either prior infection or vaccination—elicits protective responses against subsequent Mycobacterium tuberculosis (Mtb) infection. However, the changes that occur in the lung cellular milieu post-primary Mtb infection and their contributions to protection upon reinfection remain poorly understood. Using clinical and microbiological endpoints in a non-human primate reinfection model, we demonstrated that prior Mtb infection elicited a long-lasting protective response against subsequent Mtb exposure and was CD4+ T cell dependent. By analyzing data from primary infection, reinfection, and reinfection-CD4+ T cell-depleted granulomas, we found that the presence of CD4+ T cells during reinfection resulted in a less inflammatory lung milieu characterized by reprogrammed CD8+ T cells, reduced neutrophilia, and blunted type 1 immune signaling among myeloid cells. These results open avenues for developing vaccines and therapeutics that not only target lymphocytes but also modulate innate immune cells to limit tuberculosis (TB) disease. [Display omitted] • CD4+ T cells are required for protection against Mtb reinfection in macaques • Mtb reinfection promotes immuno-modulatory CD8+ T cell-biased immunity • Myeloid-derived cells downregulate gene networks implicated in TB susceptibility • Self-reinforcing cellular circuits balance host immunity in reinfection granulomas Th1 CD4+ T cells mediate protective anti- Mtb immunity across biological systems and organisms. Bromley, Ganchua, et al. demonstrate that CD4+ T cells regulate immune tone in TB granulomas and are necessary for immune recall and protection against reinfection. Following reinfection, CD4+ T cells facilitate the development of a growth restrictive niche via the induction of immuno-modulatory genes and cellular interaction networks. [ABSTRACT FROM AUTHOR]

Objective: Infective endocarditis (IE) is a severe condition characterized by high mortality rates. We aimed to assess reinfection and mortality rates in IE patients at a tertiary referral center during long-term follow-up. Patients and Methods: We retrospectively analyzed 204 patients meeting modified Duke criteria for definite IE between 2009 and 2019. Early reinfection was defined as occurrence within 6 months, and late reinfection was defined as occurrence 6 months after the initial diagnosis. Results: Mean follow-up duration was 40.3 ± 26.4 months. Valve surgery was performed in 125 patients (69.8%), while 54 (30.2%) received medical therapy alone. Early reinfection was seen in 9 patients (5.1%), and late reinfection in 12 patients (6.7%). Staphylococci (41.9%), Streptococci (26.3%), and Enterococci (15.6%) were common pathogens. Peripheral limb emboli predicted reinfection (HR 4.118, 95% CI 1.471-11.528, p=0.007). Survival rates at 1, 2, and 5 years were 70.2%, 65.7%, and 57.3%, respectively. Age (HR 1.030, 95% CI 1.011 -- 1.049, p=0.002), peripheral limb emboli (HR 2.994, 95% CI 1.509-5.940, p=0.002), and septic shock (HR 2.357, 95% CI 1.097-5.065, p=0.028) predicted mortality. Conclusion: Infective endocarditis mortality rates remain high regardless of reinfection. Peripheral limb emboli independently determine reinfection and mortality. Careful management of this group may reduce morbidity and mortality. [ABSTRACT FROM AUTHOR]

This study showed that a severe acute respiratory syndrome coronavirus 2 infection reduced the risk of reinfection among vaccinated individuals by 0.50 (95% CI, 0.39–0.64) over a 1-year period, after accounting for unreported infections using avidity-based serology. Reciprocally, chronic symptoms increased from a baseline of 21% (95% CI, 16%–28%) among infection-naïve individuals to 43% (95% CI, 30%–61%) in reinfected individuals. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear mathematical model for tuberculosis transmission, which incorporates multiple saturated exogenous reinfections, is proposed and explored. The existence of disease-free and endemic steady states is investigated. Disease-free equilibrium (DFE) is locally asymptotically stable (LAS) but not globally asymptotically stable (GAS) when the basic reproduction number, ℛ 0 < 1. However, it is GAS only when there is no exogenous reinfection. The local asymptotic stability and global asymptotic stability of the unique endemic equilibrium point (EEP) are established under certain conditions when ℛ 0 > 1. Further, the EEP is GAS when ℛ 0 > 1 , provided there is no exogenous reinfection. When ℛ 0 is below unity, the presence of multiple endemic equilibria is found which leads to backward bifurcation. It is demonstrated that the system encounters a Hopf-bifurcation when the transmission rate β crosses a critical value, resulting in the formation of limit cycles, i.e. periodic solutions bifurcate around the EEP when β passes a critical value. The stability and direction of Hopf-bifurcation are also studied. The results of the analytical work are validated through numerical simulations. A numerical simulation illustrates that EEP losses its stability via Hopf-bifurcation for specific parameters. However, when the bifurcation parameter β is increased further, the EEP regains its stability. In addition, Hopf-bifurcation occurs due to exogenous reinfection rates p and . Thus, our model shows some important nonlinear dynamical behaviors. [ABSTRACT FROM AUTHOR]

Two-stage prosthesis exchange is the treatment of choice for chronic periprosthetic joint infection (PJI) of a total hip arthroplasty (THA), especially when the bone and surrounding soft tissues are compromised or difficult-to-treat pathogens are implicated. The aims of our study were as follows: (1) to determine the outcome of 2-stage prosthesis exchange for the treatment of PJI after THA and (2) to determine the risk factors for reinfection leading to subsequent revision surgeries after reimplantation. We prospectively enrolled 187 consecutive patients who underwent a 2-stage THA exchange with resection arthroplasty for PJI from 2013 to 2019. The mean (± SD) duration of follow-up was 54.2 ± 24.9 months (range, 36 to 96), and the mean interval until reimplantation was 9.8 ± 8.9 weeks (range, 2 to 38). All patients remained in a spacer-free girdlestone situation between the 2 stages of treatment. Patients who remained infection-free after their 2-stage treatment were considered to have achieved treatment success. The overall success rate was 85.6%. The cumulative probability of reinfection was 11.5% after one year and 14% after 2 years after reimplantation. High virulence or difficult-to-treat pathogens were significant and independent risk factors for reinfection (HR [hazard ratio] = 3.71, 95% CI [confidence interval]: 1.47 to 9.36, P =.006 and HR = 3.85, 95% CI: 1.73 to 8.57, respectively, P =.001), as was previous 2-stage hip prosthesis exchange (HR = 3.58, 95% CI: 1.33 to 9.62, P =.01). Overall reoperation and revision rates were 26.2 and 16.6%, respectively. Re-infected patients had an 80% higher probability of reoperation than noninfected ones (P <.001, log-rank = 102.6), and they were 55% more likely to undergo revision surgery during their follow-up (P <.001, log-rank = 55.4). Reinfection rates after 2-stage spacer-free THA revision for PJI still remain high but are comparable to those including cement spacers. Patients who have had prior failed 2-stage implant exchanges or are infected by high-grade or difficult-to-treat pathogens are at high risk for treatment failure. [ABSTRACT FROM AUTHOR]

Purpose: Patients with non-beta-hemolytic streptococcal bacteremia (NBHSB) are at risk of infective endocarditis (IE). Patients with cardiac implantable electronic device (CIED) have been described to have an increased risk of IE. The aim of the study was to describe a population-based cohort of patients with NBHSB and CIED and variables associated with IE and recurrent NBHSB. Methods: All episodes with NBHSB in blood culture from 2015 to 2018 in a population of 1.3 million inhabitants were collected from the Clinical Microbiology Laboratory, Lund, Sweden. Through medical records, patients with CIED during NBHSB were identified and clinical data were collected. Patients were followed 365 days after NBHSB. Results: Eighty-five episodes in 79 patients with CIED and NBHSB constituted the cohort. Eight patients (10%) were diagnosed with definite IE during the first episode, five of whom also had heart valve prosthesis (HVP). In 39 patients (49%) transesophageal echocardiography (TEE) was performed of which six indicated IE. Four patients had the CIED extracted. Twenty-four patients did not survive (30%) the study period. Four patients had a recurrent infection with NBHSB with the same species, three of whom had HVP and had been evaluated with TEE with a negative result during the first episode and diagnosed with IE during the recurrency. Conclusion: The study did not find a high risk of IE in patients with NBHSB and CIED. Most cases of IE were in conjunction with a simultaneous HVP. A management algorithm is suggested. [ABSTRACT FROM AUTHOR]

The objective of the study was to compare outcomes in patients with complete surgical resection versus partial resection of diabetic foot osteomyelitis (OM). A post hoc analysis of 171 patients with OM was performed using data from two randomized clinical trials. OM was confirmed with bone culture or histopathology. Surgical culture specimens were obtained from resected bone and sent for histopathology and microbiology. Residual osteomyelitis (RO) was defined as a positive resected margin on culture or histopathology. No residual osteomyelitis (NRO) was defined as no growth from bone culture and no histopathological inflammation in the biopsy of the resection margin. Data from the 12‐month follow‐up were used to determine clinical outcomes. During the index hospitalization, NRO patients had significantly shorter duration of antibiotic therapy (NRO 21.0, 13.0–38.0 vs. RO 37.0, 20.8–50.0, p <0.01) and more amputations than patients with RO (NRO 89.9% vs. RO 60.9%, p <0.01). During the 12‐month follow‐up, patients with NRO also had significantly shorter duration of antibiotic therapy (NRO 42, 21.0–66.5 vs. RO 50.5, 35.0–75.0, p = 0.02). During the 12‐month follow‐up, there was no difference in ulceration at the same site (NRO 3.7%, RO 4.3% p = 0.85), hospitalization (NRO 32.6%, RO 34.8%, p = 0.76), total re‐infections (NRO 25.3%, RO 29.3%, p = 0.56), re‐infection with osteomyelitis (NRO 13.3% vs. 13.5%, p = 0.36), amputation (NRO 8.8%, RO 5.4%, p = 0.86) and time to wound healing in days (NRO 94, 41.0–365 vs. RO 106, 42.8–365, p = 0.77). Successful treatment of osteomyelitis was achieved by 86.7% and 86.5% of patients. During the index hospitalization, patients with no residual osteomyelitis had more amputations and were treated with antibiotics for a shorter duration. During the 12‐month follow‐up, patients with no residual osteomyelitis had shorter durations of antibiotics. There were no differences in re‐infection, amputation, re‐ulceration or hospitalization. Level of evidence: 1 [ABSTRACT FROM AUTHOR]

Abstract Background Hepatitis C virus (HCV) reinfection following successful treatment threatens the achievement of HCV elimination. The primary aim of this study is to assess reinfection rate three years after sustained virologic response (SVR) in people who inject drugs (PWID) that are on opioid agonist treatment (OAT) who underwent anti-HCV treatment with interferon-free regimens. Methods Observational, non-interventional, prospective, descriptive study carried out in Spanish tertiary public hospitals between 2017 and 2022. Participants comprised 186 adult HCV infected individuals, 85.5% males with a mean age (Standard Deviation, SD) of 50.1 (5.9). All were enrolled in an OAT program at baseline and had attained SVR 12 weeks after therapy completion with an interferon-free treatment. Baseline data were abstracted from medical chart information collected through the routine clinical practice. Results The overall rate of HCV reinfection three years after SVR12 among PWID was 1.2 new cases per 100 person-years of follow-up at a median of 15.9 months. In the subgroup analyses, those with injection drug practice and without a stable housing had higher reinfection rates. Conclusion Although PWID in OAT present a low rate of reinfection by HCV after successful treatment, a closer monitoring in the first year and strengthening inter-consultations with services responsible for monitoring addiction in these patients will be crucial to reduce risky behaviors avoiding HCV reinfection.

This study presents a novel approach for inferring the incidence of infections by employing a quantitative model of the serum antibody response. Current methodologies often overlook the cumulative effect of an individual's infection history, making it challenging to obtain a marginal distribution for antibody concentrations. Our proposed approach leverages approximate Bayesian computation to simulate cross-sectional antibody responses and compare these to observed data, factoring in the impact of repeated infections. We then assess the empirical distribution functions of the simulated and observed antibody data utilizing Kolmogorov deviance, thereby incorporating a goodness-of-fit check. This new method not only matches the computational efficiency of preceding likelihood-based analyses but also facilitates the joint estimation of antibody noise parameters. The results affirm that the predictions generated by our within-host model closely align with the observed distributions from cross-sectional samples of a well-characterized population. Our findings mirror those of likelihood-based methodologies in scenarios of low infection pressure, such as the transmission of pertussis in Europe. However, our simulations reveal that in settings of higher infection pressure, likelihood-based approaches tend to underestimate the force of infection. Thus, our novel methodology presents significant advancements in estimating infection incidence, thereby enhancing our understanding of disease dynamics in the field of epidemiology.

BackgroundBedaquiline is a life-saving tuberculosis drug undergoing global scale-up. People at risk of weak tuberculosis drug regimens are a priority for novel drug access despite the potential source of Mycobacterium tuberculosis-resistant strains. We aimed to characterise bedaquiline resistance in individuals who had sustained culture positivity during bedaquiline-based treatment.MethodsWe did a retrospective longitudinal cohort study of adults (aged ≥18 years) with culture-positive pulmonary tuberculosis who received at least 4 months of a bedaquiline-containing regimen from 12 drug-resistant tuberculosis treatment facilities in Cape Town, South Africa, between Jan 20, 2016, and Nov 20, 2017. Sputum was programmatically collected at baseline (ie, before bedaquiline initiation) and each month to monitor treatment response per the national algorithm. The last available isolate from the sputum collected at or after 4 months of bedaquiline was designated the follow-up isolate. Phenotypic drug susceptibility testing for bedaquiline was done on baseline and follow-up isolates in MGIT960 media (WHO-recommended critical concentration of 1 μg/mL). Targeted deep sequencing for Rv0678, atpE, and pepQ, as well as whole-genome sequencing were also done.FindingsIn total, 40 (31%) of 129 patients from an estimated pool were eligible for this study. Overall, three (8%) of 38 patients assessable by phenotypic drug susceptibility testing for bedaquiline had primary resistance, 18 (47%) gained resistance (acquired or reinfection), and 17 (45%) were susceptible at both baseline and follow-up. Several Rv0678 and pepQ single-nucleotide polymorphisms and indels were associated with resistance. Although variants occurred in Rv0676c and Rv1979c, these variants were not associated with resistance. Targeted deep sequencing detected low-level variants undetected by whole-genome sequencing; however, none were in genes without variants already detected by whole-genome sequencing. Patients with baseline fluoroquinolone resistance, clofazimine exposure, and four or less effective drugs were more likely to have bedaquiline-resistant gain. Resistance gain was primarily due to acquisition; however, some reinfection by resistant strains occurred.InterpretationBedaquiline-resistance gain, for which we identified risk factors, was common in these programmatically treated patients with sustained culture positivity. Our study highlights risks associated with implementing life-saving new drugs and shows evidence of bedaquiline-resistance transmission. Routine drug susceptibility testing should urgently accompany scale-up of new drugs; however, rapid drug susceptibility testing for bedaquiline remains challenging given the diversity of variants observed.FundingDoris Duke Charitable Foundation, US National Institute of Allergy and Infectious Diseases, South African Medical Research Council, National Research Foundation, Research Foundation Flanders, Stellenbosch University Faculty of Medicine Health Sciences, South African National Research Foundation, Swiss National Science Foundation, and Wellcome Trust.

Abstract Introduction Reinfection with SARS-Cov-2 after recovery can occur that most of them don’t require hospitalization. The aim of this study is estimation of out-patient COVID-19 reinfection and recurrence rates and its associated factors among Iranian patients with history of confirmed SARS-Cov-2 infection and hospitalization. Methods This study is a retrospective cohort conducted from May 2021 to May 2022 in Iran. The national Medical Care Monitoring Center (MCMC) database, obtained from the Ministry of Health and Medical Education, includes all information about confirmed COVID-19 patients who are hospitalized and diagnosed during the pandemic. Using probability proportional to size sampling from 31 provinces, 1,532 patients over one years of age with a history of hospitalization in the MCMC data are randomly selected. After that, interviews by phone are performed with all of the selected patients using a researcher-made questionnaire about the occurrence of overall reinfection without considering the time of infection occurrence, reinfection occurring at least 90 days after the discharge and recurrence (occurring within 90 days after discharge). Univariate and multivariable Cox regression analyses are performed to assess the factors associated with each index. All of the analyses are performed using Stata software version 16. Results In general, 1,532 phone calls are made, out of which 1,095 individuals are willing to participate in the study (response rate ≃ 71%). After assessing the 1,095 patients with a positive history of COVID-19, the rates of non-hospitalized overall SARS-Cov-2 reinfection, reinfection and recurrence are 122.64, 114.09, and 8.55 per 1,000 person-years, respectively. The age range of 19–64 years (aHR:3.93, 95%CI : 1.24–12.41) and COVID-19-related healthcare worker (aHR: 3.67, 95%CI: 1.77–7.61) are identified as risk factors for reinfection, while having comorbidity, being fully vaccinated, and having a partial pressure of oxygen (PaO2) ≥ 93 mmHg during the initial infection are identified as factors that reduce the risk of non-hospitalized reinfection. Conclusion Reinfection due to COVID-19 is possible because of the weakened immune system for various reasons and the mutation of the virus. Vaccination, timely boosters, and adherence to preventive measures can help mitigate this risk.

Background: With the continuation of the COVID-19 pandemic, some COVID-19 patients have a risk of SARS-CoV-2 reinfection. Viral gene sequencing has found that some of these patients were reinfected by a different and others by the same strains. This has raised concerns about the effectiveness of immunity after infection and the reliability of vaccination. We conducted a survey study to assess the characteristics of patients with reinfection and possible causes. Methods and Results: An online survey study was conducted in October 2021 on Facebook social media. This study included 2413 respondents: 1315 subjects received the BNT162b2 mRNA-based Vaccine (Pfizer/BioNTech), 811 received the ChAdOx1 (AZD1222) adenoviral vector vaccine (Oxford–AstraZeneca), and 287 received the Sinopharm inactivated COVID-10 vaccine (BBIBP-CorV). The Pfizer/BioNTech vaccine appeared to be the most effective (84%) in preventing reinfection compared to the Oxford–AstraZeneca vaccine (79%) and the Sinopharm vaccine (70%) (P

Abstract Background Reinfection rates after two-stage revision (TSR) for prosthetic joint infection (PJI) range from 7.9 to 14%. Many factors, including sinus tracts, are associated with reinfection after this procedure. This study aimed to delineate whether the presence of sinus tract could increase reinfection rate after TSR and to investigate other potential risk factors for reinfection after TSR. Methods We conducted a case-control study by retrospectively reviewing patients who underwent TSR for prosthetic hip joint infection from 2002 to 2022. The case group included patients who developed reinfection after TSR, while the control group consisted of patients who did not experience reinfection. PJI and reinfection after TSR were defined based on Delphi-based international consensus criteria. Patient demographics, past medical history, clinical manifestations, laboratory results, interval between stages, microbiological culture results were collected. Univariate analyses were utilized to assess the effect of sinus tract on reinfection and to identify other risk factors for reinfection after TSR. Results Six patients with reinfection after TSR were included as the case group and 32 patients without reinfection were in the control group. Significant difference was observed in percentage of patients with sinus tracts between the two groups (67% in the case group versus 19% in the control group, p = 0.031, OR = 8.7). Significant difference was also found in percentage of patients with positive cultures of synovial fluid and synovium harvested during the first-stage revision between the two groups (100% in the case group versus 50% in the control group, p = 0.030). Additionally, patients in the case group had a significantly higher C-reactive protein (CRP) level prior to the second stage revision than that of patients in the control group (8.80 mg/L versus 2.36 mg/L, p = 0.005), despite normal CRP levels in all patients. Conclusions Our study revealed that the presence of sinus tracts could significantly increase risk of postoperative reinfection after TSR. Positive cultures during the first stage revision and elevated CRP level prior to the second stage revision could also increase the risk of reinfection after TSR. Further studies with a larger sample size are required. Trial registration Retrospectively registered.

The effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection persist months and years after recovery. We conducted an online survey to assess the health condition of convalescents approximately 5 months following the primary infection of SARS-CoV-2. The study recruited 5,510 individuals who were primary infected, 626 participants who had experienced reinfection, and 521 participants who were without infective history. The most common disorders after the primary infection group were fatigue (15.18 %), memory issue (13.13 %), post-exertional malaise (PEM, 11.68 %), and brain fog (11.29 %) at the time of survey. In addition, SARS-CoV-2 infection had an impact on the reproductive systems. In stepwise logistic regression analysis, smoking currently, with background diseases, and outpatient visits in the acute phase could be associated with moderate / severe disorders. Further analysis of different background diseases showed that allergic rhinitis, hyperlipidemia, cardiovascular disease, autoimmune diseases, neurological diseases, and asthma likely increased the risk of moderate/severe disorders. The probability of developing disorders of individuals with SARS-CoV-2 reinfection was higher before the secondary infection than uninfected people. Fatigue, PEM, muscle pain/spasms, chills, joint pain, excessive sweating at rest, headache / dizziness, sore throat or foreign body sensation in the throat, cough, expectoration, dry / painful / watery eyes, loss of appetite and constipation were associated with an increased risk of reinfection. It was essential to undertake further research with enhanced randomization in a larger sample in the community, and to strengthen the validation of the research conclusions. The findings of this study contribute to a deeper understanding of the health recovery process among coronavirus disease 2019 (COVID-19) convalescents. Moreover, the findings help identify characteristic health risk factors associated with convalescents and highlight the risk of moderate / severe disorders and reinfection. Furthermore, the findings also provide valuable guidance and reference for SARS-CoV-2 rehabilitation strategies and the prevention of reinfection, offering insights for scientific recommendations.

Abstract Background To assess pregnancy outcomes in women with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. Methods This was a retrospective cohort study that included pregnant women who contracted coronavirus disease 2019 (COVID-19) once or twice during pregnancy and who gave birth between 1 October 2022 and 15 August 2023 in Shanghai First Maternity and Infant Hospital (Shanghai, China). We collected their clinical data and compared the frequency of adverse pregnancy outcomes between the reinfection group and the primary infection group, such as preterm birth, fetal growth restriction (FGR), hypertensive disorders of pregnancy (HDP), common pregnancy-related conditions, birth weight, and neonatal unit admission. Results We observed a 7.7% reinfection rate among the 1,405 women who contracted COVID-19 during pregnancy. There were no significant differences in the frequency of preterm birth, FGR, HDP, other common pregnancy-related conditions, birth weight, or rate of neonatal unit admission between the reinfection and single infection groups. All our participants were unvaccinated, and all had mild symptoms. Conclusion Our study showed no significant association between SARS-CoV-2 reinfection and adverse pregnancy outcomes.

The objective of the study was to identify risk factors for reintroduction of Actinobacillus pleuopneumoniae and Mycoplasma hyopneumoniae (enzootic pneumonia) onto pig farms in areas in Switzerland that were involved in an eradication programme from 1996 to 1999 and to assess the role of dealers in relation to these reinfections. The study was based on the comparison of pig farms that were reinfected in the year 2000 (cases) and pig farms that remained uninfected in the same area (controls). Additionally, data were collected from Swiss pig dealers and transport companies. Out of a total of 3983 farms, 107 farms were reinfected in the year 2000. The incidences were 0.1% for Actinobacillus pleuopneumoniae and 2.6% for Mycoplasma hyopneumoniae (enzootic pneumonia). Compared to reinfection rates prior to the eradication programme, this is a considerable reduction. Statistically significant risk factors for the reinfection were 'finishing farm', 'large mixed breeding-finishing farm', 'reinfected neighbour' and 'parking site for pig transport vehicles close to the farm'. Pig farmers that purchased pigs from only one supplier per batch had a lower risk of reintroducing infection (protective factor). As long as infected and uninfected regions co-exist in Switzerland, direct and indirect contact between farms, pig herds and slaughter sites via transport vehicles are a major pathway of disease spread. Risk management measures linked to these contacts are therefore of key importance. The survey of dealers indicated various areas for improvement such as strategic planning of pick-up routes or cleaning and disinfecting of trucks. [ABSTRACT FROM AUTHOR]

Introduction: Reinfection with SARS-Cov-2 after recovery can occur that most of them don't require hospitalization. The aim of this study is estimation of out-patient COVID-19 reinfection and recurrence rates and its associated factors among Iranian patients with history of confirmed SARS-Cov-2 infection and hospitalization. Methods: This study is a retrospective cohort conducted from May 2021 to May 2022 in Iran. The national Medical Care Monitoring Center (MCMC) database, obtained from the Ministry of Health and Medical Education, includes all information about confirmed COVID-19 patients who are hospitalized and diagnosed during the pandemic. Using probability proportional to size sampling from 31 provinces, 1,532 patients over one years of age with a history of hospitalization in the MCMC data are randomly selected. After that, interviews by phone are performed with all of the selected patients using a researcher-made questionnaire about the occurrence of overall reinfection without considering the time of infection occurrence, reinfection occurring at least 90 days after the discharge and recurrence (occurring within 90 days after discharge). Univariate and multivariable Cox regression analyses are performed to assess the factors associated with each index. All of the analyses are performed using Stata software version 16. Results: In general, 1,532 phone calls are made, out of which 1,095 individuals are willing to participate in the study (response rate ≃ 71%). After assessing the 1,095 patients with a positive history of COVID-19, the rates of non-hospitalized overall SARS-Cov-2 reinfection, reinfection and recurrence are 122.64, 114.09, and 8.55 per 1,000 person-years, respectively. The age range of 19–64 years (aHR:3.93, 95%CI : 1.24–12.41) and COVID-19-related healthcare worker (aHR: 3.67, 95%CI: 1.77–7.61) are identified as risk factors for reinfection, while having comorbidity, being fully vaccinated, and having a partial pressure of oxygen (PaO2) ≥ 93 mmHg during the initial infection are identified as factors that reduce the risk of non-hospitalized reinfection. Conclusion: Reinfection due to COVID-19 is possible because of the weakened immune system for various reasons and the mutation of the virus. Vaccination, timely boosters, and adherence to preventive measures can help mitigate this risk. [ABSTRACT FROM AUTHOR]

A stochastic susceptible–infected–recovered–infected (SIRI) epidemic model with relapse and reinfection is established in this paper. First, we prove that the solution to the epidemic model is unique and globally positive. Next, we determine some sufficient conditions for the extinction of the disease when ℛ0s < 1 and for the persistence in mean in the case of ℛ0s̄ > 1. Furthermore, we prove the existence of at least one ergodic stationary distribution of the stochastic model if ℛ0s̄ > 1. Additionally, by solving the corresponding three-dimensional Fokker–Planck equation, it is theoretically shown that the epidemic model has a log-normal probability density function when ℛ0s̄ > 1, then we obtain the exact expression of density function of the stationary distribution. Finally, we give some numerical simulations to support our theoretical results. [ABSTRACT FROM AUTHOR]

Simple Summary: Immunoglobulin (Ig) replacement therapy (IgRT) consists of the administration of low-doses human polyclonal Igs for the treatment of primary and secondary hypogammaglobulinemia, characterized by low serum levels of immunoglobulins that is associated with recurrent infections and immune dysfunction. In this review, we focus on the application and efficacy of therapeutic Igs for the management of multiple myeloma (MM) patients affected by secondary hypogammaglobulinemia that is associated with poor patients' outcome. The use of IgRT restores physiological antibody levels and stimulates innate and adaptive immune responses as well. Therefore, in MM settings the IgRT has shown a significant positive impact on infection rates increasing the patients' overall health status that correlates to a decrease in long-term complications and hospitalization and to an improved therapeutic adherence and patients' quality of life. Immunoglobulin (Ig) replacement therapy (IgRT) consists of the administration of low-dose human polyclonal Igs for the treatment of primary and secondary hypogammaglobulinemia that are associated with recurrent infections and immune dysfunction. IgRT restores physiological antibody levels and induces an immunomodulatory effect by strengthening immune effector cells, thus reducing infections. Here, we describe the pharmacology of different Ig formulations with a particular focus on their mechanism of action as low-dose IgRT, including the direct anti-microbial effect and the immunomodulatory function. In addition, we describe the use of therapeutic Igs for the management of multiple myeloma (MM), a hematologic malignancy characterized by severe secondary hypogammaglobulinemia associated with poor patient outcome. In MM settings, IgRT prevents life-threatening and recurrent infections showing promising results regarding patient survival and quality of life. Nevertheless, the clinical benefits of IgRT are still controversial. A deeper understanding of the immune-mediated effects of low-dose IgRT will provide the basis for novel combined therapeutic options and personalized therapy in MM and other conditions characterized by hypogammaglobulinemia. [ABSTRACT FROM AUTHOR]

Detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfections is challenging with current serology assays and is further complicated by the marked decrease in routine viral testing practices as viral transmission increased during Omicron. Here, we provide proof-of-principle that high-avidity anti-nucleocapsid (N) antibodies detects reinfections after a single infection with higher specificity (85%; 95% confidence interval [95% CI], 80%–90%) compared to anti-N antibody levels (72%; 95% CI, 66%–79%) in a vaccinated cohort. This method could be used to retroactively investigate the epidemiology and incremental long-term health consequences of SARS-CoV-2 reinfections. [ABSTRACT FROM AUTHOR]

Background: Reinfection rates after two-stage revision (TSR) for prosthetic joint infection (PJI) range from 7.9 to 14%. Many factors, including sinus tracts, are associated with reinfection after this procedure. This study aimed to delineate whether the presence of sinus tract could increase reinfection rate after TSR and to investigate other potential risk factors for reinfection after TSR. Methods: We conducted a case-control study by retrospectively reviewing patients who underwent TSR for prosthetic hip joint infection from 2002 to 2022. The case group included patients who developed reinfection after TSR, while the control group consisted of patients who did not experience reinfection. PJI and reinfection after TSR were defined based on Delphi-based international consensus criteria. Patient demographics, past medical history, clinical manifestations, laboratory results, interval between stages, microbiological culture results were collected. Univariate analyses were utilized to assess the effect of sinus tract on reinfection and to identify other risk factors for reinfection after TSR. Results: Six patients with reinfection after TSR were included as the case group and 32 patients without reinfection were in the control group. Significant difference was observed in percentage of patients with sinus tracts between the two groups (67% in the case group versus 19% in the control group, p = 0.031, OR = 8.7). Significant difference was also found in percentage of patients with positive cultures of synovial fluid and synovium harvested during the first-stage revision between the two groups (100% in the case group versus 50% in the control group, p = 0.030). Additionally, patients in the case group had a significantly higher C-reactive protein (CRP) level prior to the second stage revision than that of patients in the control group (8.80 mg/L versus 2.36 mg/L, p = 0.005), despite normal CRP levels in all patients. Conclusions: Our study revealed that the presence of sinus tracts could significantly increase risk of postoperative reinfection after TSR. Positive cultures during the first stage revision and elevated CRP level prior to the second stage revision could also increase the risk of reinfection after TSR. Further studies with a larger sample size are required. Trial registration: Retrospectively registered. [ABSTRACT FROM AUTHOR]

Recent studies suggest an increased risk of reinfection with the SARS-CoV-2 Omicron variant compared with previous variants, potentially due to an increased ability to escape immunity specific to older variants, high antigenic divergence of Omicron from earlier virus variants as well as its altered cell entry pathway. The present study sought to investigate epidemiological evidence for differential SARS-CoV-2 reinfection intervals and incidence rates for the Delta versus Omicron variants within Wales. Reinfections in Wales up to February 2022 were defined using genotyping and whole genome sequencing. The median inter-infection intervals for Delta and Omicron were 226 and 192 days, respectively. An incidence rate ratio of 2.17 for reinfection with Omicron compared to Delta was estimated using a conditional Poisson model, which accounted for several factors including sample collection date, age group, area of residence, vaccination and travel status. These findings are consistent with an increased risk of reinfection with the Omicron variant, and highlight the value of monitoring emerging variants that have the potential for causing further waves of cases. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to assess COVID-19 re-infection rates among individuals previously infected between 2020 and November 2022, particularly during the first wave of high-intensity transmission, and to identify the risk factors associated with re-infection in Jiangsu Province, China. Methodology: Epidemiological investigations were conducted through telephone interviews and face-to-face visits in February and March 2023. Statistical analyses included the Chi-square or Fisher's exact test for categorical data, Student's Mest for numerical data, Poisson regression for influencing factors, and Kaplan-Meier for cumulative re-infection risk. Results: Among 12,910 individuals surveyed, 957 (7.4%) cases of re-infection were identified. Re-infection rates varied significantly by initial infection period: 42.5% in January-February 2020, 15.5% in July-August 2021, 6.7% in March-April 2022, and 1.1% in September-October 2022. Females and individuals aged 18-50 years were more susceptible to re-infection. A reduced risk of re-infection was observed in those who received four vaccine doses, with a relative risk of 0.25 (p = 0.019). Conclusions: For populations prone to COVID-19 re-infections, particularly females and young adults aged 18-50 years, receiving four or more vaccine doses effectively reduces the likelihood of repeated infections. These findings emphasize the need to prioritize vaccination and protect high-risk groups in COVID-19 prevention efforts. [ABSTRACT FROM AUTHOR]

Introduction: The coronavirus disease 2019 (COVID-19) pandemic is a global health concern and has persisted through the emergence of variants that have caused subsequent waves of COVID-19 due to the high dispersion and contagiousness of the virus. The aim of this work was to analyze the epidemiology of the cases of reinfection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants during the third and fourth wave of the COVID-19 pandemic at the Hospital Juárez de México (HJM). Methodology: A prospective study of the cases of SARS-CoV-2 reinfection, variants detected, symptoms, and associated comorbidities was carried out on 1,347 patients who attended the HJM from September 2021 to July 2022. Results: 760 (56.4%) and 587 (43.6%) patients were negative and positive for SARS-CoV-2, respectively. The Omicron variant was the most frequent and the most common symptoms were: cough (80%), headache (61.32%), fever (51.6%), and dyspnea (40%). A higher proportion of females were vaccinated, ranging from one dose to the complete schedule. The factors that were associated with a greater risk of death from complications of SARS-CoV-2 reinfection were male gender, diabetes mellitus, and arterial hypertension. Conclusions: Females were the most susceptible to an Omicron reinfection event, even though they were vaccinated. However, the risk of death was higher when the patient was male; being male was a potential risk factor for death from COVID-19 and comorbidities. [ABSTRACT FROM AUTHOR]

This paper discusses the application of reactive multiparticle collision (RMPC) dynamics, a particle-based method, to epidemic models. First, we consider a susceptible-infectious-recovered framework to obtain data on contacts of susceptibles with infectious people in a population. It is found that the number of contacts increases and the contact duration decreases with increases in the disease transmission rate and average population speed. Next, we obtain reinfection statistics for a general infectious disease from RMPC simulations of a susceptible-infectious-recovered-susceptible model. Finally, we simulate a susceptible-exposed-infectious-recovered model and gather the exposure, infection, and recovery time for the individuals in the population under consideration. It is worth mentioning that we can collect data in the form of average contact duration, average initial infection time, etc., from RMPC simulations of these models, which is not possible with population-based stochastic models, or deterministic systems. This study provides quantitative insights on the potential of RMPC to simulate epidemic models and motivates future efforts for its application in the field of mathematical epidemiology. [ABSTRACT FROM AUTHOR]

Background We aimed to examine the association among nucleocapsid (N) antibodies, a combination of N and spike (S) antibodies, and protection against SARS-CoV-2 reinfection. Methods We conducted a prospective cohort study among staff at a national medical research center in Tokyo and followed them for the incidence of SARS-CoV-2 infection between June and September 2023 (Omicron XBB.1.16/EG.5 wave). At baseline, participants donated blood samples to measure N- and S-specific antibodies. Cox regression was used to estimate the hazard ratio and protection ([1 – hazard ratio] × 100) against subsequent SARS-CoV-2 infection across these antibody levels. Results Among participants with previous infection, higher pre-reinfection N antibodies were associated with a lower risk of reinfection, even after adjusting S antibody levels (P <.01 for trend). Estimation of the protection matrix for N and S antibodies revealed that high levels in N and S antibodies conferred robust protection (>90%) against subsequent infection. In addition, a pattern of low pre-reinfection N antibodies but high vaccine-enhanced S antibodies showed high protection (>80%). Conclusions Pre-reinfection N antibody levels correlated with protection against reinfection, independent of S antibodies. If the N antibodies were low, vaccine-boosted S antibodies might enhance the reinfection protection. [ABSTRACT FROM AUTHOR]