Search

Background Data on protection afforded by updated coronavirus disease 2019 (COVID-19) vaccines (bivalent/XBB 1.5 monovalent) against the emergent JN.1 variant remain limited. Methods We conducted a retrospective population-based cohort study among all boosted Singaporeans aged ≥18 years during a COVID-19 wave predominantly driven by JN.1, from 26 November 2023 to 13 January 2024. Multivariable Cox regression was used to assess risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19–associated emergency department (ED) visits/hospitalizations, stratified by vaccination status/prior infection; with individuals last boosted ≥1 year used as the reference category. Vaccination and infection status were classified using national registries. Results A total of 3 086 562 boosted adult Singaporeans were included in the study population, accounting for 146 863 476 person-days of observation. During the JN.1 outbreak, 28 160 SARS-CoV-2 infections were recorded, with 2926 hospitalizations and 3747 ED visits. Compared with individuals last boosted ≥1 year earlier with ancestral monovalent vaccines, receipt of an updated XBB.1.5 booster 8–120 days earlier was associated with lower risk of JN.1 infection (adjusted hazard ratio [aHR], 0.59 [95% confidence interval (CI),.52–.66]), COVID-19–associated ED visits (0.50 [.34–.73]), and hospitalizations (0.58 [.37–.91]), while receipt of a bivalent booster 121–365 days earlier was associated with lower risk of JN.1 infection (0.92 [.88–.95]) and ED visits (0.80 [.70–.90]). Lower risk of COVID-19 hospitalization during the JN.1 outbreak (aHR, 0.57 [95% CI,.33–.97]) was still observed following receipt of an updated XBB.1.5 booster 8–120 days earlier, even when analysis was restricted to previously infected individuals. Conclusions Recent receipt of updated boosters conferred protection against SARS-CoV-2 infection and ED visits/hospitalizations during a JN.1 variant wave, in both previously infected and uninfected individuals. Annual booster doses confer protection during COVID-19 endemicity. [ABSTRACT FROM AUTHOR]

Socio-economic status (SES) disparities exist in the uptake of COVID-19 vaccination; however, most studies were conducted during the initial pandemic wave when vaccination was less discretionary, limiting generalizability. We aimed to determine whether differences in vaccination uptake across SES strata widened after the removal of vaccination-differentiated measures prior to the rollout of the second boosters, in a nationwide cohort of older Singaporeans at higher risk of severe-COVID-19. Retrospective population-based cohort study. Retrospective population-based cohort study of all Singaporeans aged ≥60 years from 22nd February 2021–14th February 2023. Cox regression models controlling for demographics and comorbidities were used to estimate hazard-ratios (HRs) for the uptake of primary vaccination as well as first/second boosters, as recorded in the national vaccination registry, according to SES (housing type). 836,170 individuals were included for completion of a primary vaccine series; 784,938 individuals for completion of the first booster and 734,206 individuals for the completion of the second booster. Differences in vaccination uptake by SES strata were observed (e.g. vaccination uptake in lowest-SES [1–2 room public-housing] versus highest-SES [private housing]: second booster, 47.6% vs. 58.1%; first booster, 93.9% vs. 98.0%). However, relative differences did not markedly widen during second booster rollout when vaccination was more discretionary (e.g. amongst those aged 60–69 years: 0.75 [95% CI = 0.73–0.76] for the first booster; 0.81 [95% CI = 0.79–0.84] for the second booster). While differences in vaccination uptake across SES strata by housing type persisted during the rollout of primary vaccination and subsequent boosters in a nationwide cohort of older Singaporeans, differences did not widen substantially when vaccination was made more discretionary. [ABSTRACT FROM AUTHOR]

Background Literature on long-term real-world vaccine effectiveness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) booster vaccines (up to and beyond 360 days) is scarce. We report estimates of protection against symptomatic infection, emergency department (ED) attendances and hospitalizations up to and beyond 360 days post-receipt of booster messenger RNA (mRNA) vaccines among Singaporeans aged ≥60 years during an Omicron XBB wave. Methods We conducted a population-based cohort study including all Singaporeans aged ≥60 years with no documented prior SARS-CoV-2 infection who had previously received ≥3 doses of mRNA vaccines (BNT162b2/mRNA-1273), over a 4-month period during transmission of Omicron XBB. We reported the adjusted incidence-rate-ratio (IRR) for symptomatic infections, ED attendances and hospitalizations at different time-intervals from both first and second boosters, using Poisson regression; with the reference group being those who received their first booster 90 to 179 days prior. Results In total, 506 856 boosted adults were included, contributing 55 846 165 person-days of observation. Protection against symptomatic infections among those who received a third vaccine dose (first booster) waned after 180 days with increasing adjusted IRRs; however, protection against ED attendances and hospitalizations held up, with comparable adjusted IRRs with increasing time from third vaccine doses (≥360 days from third dose: adjusted IRR [ED attendances] = 0.73, 95% confidence interval [CI] =.62–.85; adjusted IRR [hospitalization] = 0.58, 95% CI =.49–.70). Conclusions Our results highlight the benefit of a booster dose in reducing ED attendances and hospitalizations amongst older adults aged ≥60 years with no documented prior SARS-CoV-2 infection, during an Omicron XBB wave; up to and beyond 360 days post-booster. A second booster provided further reduction. [ABSTRACT FROM AUTHOR]

Importance: Assessing population-wide risk-benefit ratio of COVID-19 vaccination remains relevant in the current era of Omicron endemicity and boosting. Assessments of mortality risk and cardiovascular events post-vaccination/infection were generally made prior to emergence of milder Omicron and booster rollout., Methods: Retrospective cohort study from 6th January to 31st December 2022 (Omicron-predominant transmission), amongst adult Singaporeans aged ≥18 years. Cox regression models adjusted for demographics/comorbidities were used to estimate risk of all-cause mortality and cardiovascular events 0-180 days post-mRNA vaccination/SARS-CoV-2 infection, compared to >180 days post-mRNA vaccination. Risk periods post-vaccination were further stratified by presence/absence of SARS-CoV-2 infection in the preceding 180 days; similarly, risk periods post-infection were further stratified by vaccination in the 180 days preceding infection., Results: 3,137,210 adults participated, with 2,047,008 vaccine doses administered (99 % being booster doses) and 1,189,846 infections. 23,028 deaths and 54,017 cardiac events were recorded. No elevated risk of all-cause mortality/cardiovascular events was observed across all age strata post-vaccination. Conversely, all-cause mortality post-infection remained elevated up to >180 days in older adults (≥60 years), compared to person-time > 180 days post-vaccination. For vaccine-breakthrough SARS-CoV-2 infection in older adults vaccinated <180 days prior, risk of mortality was only elevated up to 60 days post-infection, but not beyond. Elevated risk of cardiovascular events 1-2 months after any SARS-CoV-2 infection was observed across all age strata, with elevated risk observed in older adults >180 days post-infection (adjusted-hazards-ratio, aHR = 1.18, 95 %CI = 1.04-1.34). Preceding vaccination within 180 days prior to infection attenuated this risk, with no significantly elevated post-acute risk of cardiovascular events (>180 days: aHR = 1.10, 95 %CI = 0.95-1.07)., Conclusion: No increased risk of all-cause mortality or cardiovascular events was observed up to 180 days after any mRNA vaccination dose in the Omicron era; vaccination attenuated post-acute cardiovascular risk in older adults. The risk-benefit ratio of vaccination remained positive during Omicron., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors report no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background In view of waning antitoxin titres over time after the last vaccine dose against diphtheria and tetanus, we determined the immunity levels in adults to identify most susceptible groups for protection in Singapore. Methods Our study involved residual sera from 3293 adults aged 18-79 who had participated in a national health survey in 2010. IgG antibody levels were determined using commercial enzyme-linked immunosorbent assay. Results Overall, 92.0% (95% confidence interval [CI]: 91.1-92.9%) had at least basic protection against diphtheria (antibody levels >0.01 IU/ml), while 71.4% (95% CI: 69.8-72.9%) had at least short-term protection against tetanus (antibody levels .0.1 IU/ml). The seroprevalence declined significantly with age for both diseases; the drop was most marked in the 50-to 59-year age group for diphtheria and 60-to 69-year age group for tetanus. There was a significant difference in seroprevalence by residency for diphtheria (92.8% among Singapore citizens versus 87.1 % among permanent residents; P -- 0.001). The seroprevalence for tetanus was significantly higher among males (83.2%) than females (62.4%) (P, 0.0005). Conclusions It maybe of value to consider additional vaccination efforts to protect older adults at higher risk for exposure against diphtheria and tetanus, particularly those travelling to areas where diphtheria is endemic or epidemic. [ABSTRACT FROM AUTHOR]

Abstract: Since the introduction of the pertussis vaccine into the standard immunization program, very few cases of pertussis have been detected. In 2007, it was felt that the number of cases being admitted for pertussis had increased and this was verified on a retrospective review done from 2004 to 2007 of children diagnosed with pertussis in KK Women''s and Children''s Hospital. Aim: To review the cases diagnosed with pertussis, the demographic profile and the outcome of these patients. Methods: A retrospective review was done of patients diagnosed with pertussis from 2004 to 2007. The patients were identified from records of the positive results obtained from the microbiology laboratory. Results: In the preceding years, only 1–2 cases/year were reported with pertussis but this increased to 33 cases in 2007. 45 confirmed cases were analysed. Most infections were in infants below 6 months old (mean age 4.1 months) and almost all were not vaccinated. The average length of stay was 4.96 days (Range 2–14 days, SD 2.55). Children under 6 months had more severe disease in terms of ICU admissions (6% vs. 0%, p =0.70) and average length of stay (5.1 vs. 3.5 days, p =0.25) as compared to those above 6 months of age. Exposure to a symptomatic adult was documented in 64%, mainly parents (45%), older siblings (29%). Healthcare workers may also be a source of infection as one child had symptoms as early as the first week of life and none of the family members were coughing. Conclusion: There is a resurgence of pertussis in recent years with high morbidity in children who have not been vaccinated. A booster with Tdap vaccine should be considered for young adults and healthcare workers looking after children. [Copyright &y& Elsevier]

Background: Protecting young children from pandemic influenza should also reduce transmission to susceptible adults, including pregnant women., Methods: An open study assessed immunogenicity and reactogenicity of a heterologous booster dose of A/turkey/Turkey/1/2005(H5N1)-AS03B (AS03B is an Adjuvant System containing α-tocopherol and squalene in an oil-in-water emulsion [5.93 mg tocopherol]) in infants and children aged 6 to <36 months that was given 6 months following 2-dose primary vaccination with A/Indonesia/05/2005(H5N1)-AS03B. Vaccines contained 1.9 µg of hemagglutinin antigen and AS03B. Hemagglutinin inhibition (HI) responses, microneutralization titers, and antineuraminidase antibody levels were assessed for 6 months following the booster vaccination., Results: For each age stratum (defined on the basis of the subject's age at first vaccination as 6 to <12 months, 12 to <24 months, and 24 to <36 months) and overall (n=113), European influenza vaccine licensure criteria were fulfilled for responses to A/turkey/Turkey/1/2005(H5N1) 10 days following the booster vaccination. Local pain and fever increased with consecutive doses. Anamnestic immune responses were demonstrated for HI, neutralizing, and antineuraminidase antibodies against vaccine-homologous/heterologous strains. Antibody responses to vaccine-homologous/heterologous strains persisted in all children 6 months following the booster vaccination., Conclusions: Prevaccination of young children with a clade 2 strain influenza A(H5N1) AS03-adjuvanted vaccine followed by heterologous booster vaccination boosted immune responses to the homologous strain and a related clade, with persistence for at least 6 months. The results support a prime-boost vaccination approach in young children for pandemic influenza preparedness., Clinical Trials Registration: NCT01323946., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.)