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Background Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among US infants. A child's calendar birth month determines their age at first exposure(s) to RSV. We estimated birth month-specific risk of medically attended (MA) RSV lower respiratory tract infection (LRTI) among infants during their first RSV season and first year of life (FYOL). Methods We analyzed infants born in the USA between July 2016 and February 2020 using three insurance claims databases (two commercial, one Medicaid). We classified infants' first MA RSV LRTI episode by the highest level of care incurred (outpatient, emergency department, or inpatient), employing specific and sensitive diagnostic coding algorithms to define index RSV diagnoses. In our main analysis, we focused on infants' first RSV season. In our secondary analysis, we compared the risk of MA RSV LRTI during infants' first RSV season to that of their FYOL. Results Infants born from May through September generally had the highest risk of first-season MA RSV LRTI—approximately 6–10% under the specific RSV index diagnosis definition and 16–26% under the sensitive. Infants born between October and December had the highest risk of RSV-related hospitalization during their first season. The proportion of MA RSV LRTI events classified as inpatient ranged from 9% to 54% (specific) and 5% to 33% (sensitive) across birth month and comorbidity group. Through the FYOL, the overall risk of MA RSV LRTI is comparable across birth months within each claims database (6–11% under the specific definition, 17–30% under the sensitive), with additional cases progressing to care at outpatient or ED settings. Conclusions Our data support recent national recommendations for the use of nirsevimab in the USA. For infants born at the tail end of an RSV season who do not receive nirsevimab, a dose administered prior to the onset of their second RSV season could reduce the incidence of outpatient- and ED-related events. [ABSTRACT FROM AUTHOR]

Background High-dose (HD) influenza vaccine offers improved protection from influenza virus infection among older adults compared with standard-dose (SD) vaccine. Here, we explored whether HD vaccine attenuates disease severity among older adults with breakthrough influenza. Methods This was a retrospective cohort study of US claims data for influenza seasons 2016–2017, 2017–2018, and 2018–2019, defined as 1 October through 30 April, among adults aged ≥65 years. After adjusting the different cohorts for the probability of vaccination conditional on patients' characteristics, we compared 30-day mortality rate post-influenza among older adults who experienced breakthrough infection after receipt of HD or SD influenza vaccines and among those not vaccinated (NV). Results We evaluated 44 456 influenza cases: 23 109 (52%) were unvaccinated, 15 037 (33.8%) received HD vaccine, and 6310 (14.2%) received SD vaccine. Significant reductions in mortality rates among breakthrough cases were observed across all 3 seasons for HD vs NV, ranging from 17% to 29% reductions. A significant mortality reduction of 25% was associated with SD vaccination vs NV in the 2016–2017 season when there was a good match between circulating influenza viruses and selected vaccine strains. When comparing HD vs SD cohorts, mortality reductions were higher among those who received HD in the last 2 seasons when mismatch between vaccine strains and circulating H3N2 viruses was documented, albeit not significant. Conclusions HD vaccination was associated with lower post-influenza mortality among older adults with breakthrough influenza, even during seasons when antigenically drifted H3N2 circulated. Improved understanding of the impact of different vaccines on attenuating disease severity is warranted when assessing vaccine policy recommendations. [ABSTRACT FROM AUTHOR]

Background WHO estimates that seasonal influenza epidemics result in three to five million cases of severe illness (hospitalisations) every year. We aimed to improve the understanding of influenza-associated hospitalisation estimates at a national and global level. Methods We performed a systematic literature review of English- and Chinese-language studies published between 1995 and 2020 estimating influenza-associated hospitalisation. We included a total of 127 studies (seven in Chinese) in the meta-analysis and analyzed their data using a logit-logistic regression model to understand the influence of five study factors and produce national and global estimates by age groups. The five study factors assessed were: 1) the method used to calculate the influenza-associated hospitalisation estimates (rateor time series regression-based), 2) the outcome measure (divided into three envelopes: narrow, medium, or wide), 3) whether every case was laboratory-confirmed or not, 4) whether the estimates were national or sub-national, 5) whether the rates were based on a single year or multiple years. Results The overall pooled influenza-associated hospitalisation rate was 40.5 (95% confidence interval (CI) = 24.3-67.4) per 100 000 persons, with rates varying substantially by age: 224.0 (95% CI = 118.8-420.0) in children aged 0-4 years and 96.8 (95% CI = 57.0-164.3) in the elderly aged >65 years. The overall pooled hospitalisation rates varied by calculation method; for all ages, the rates were significantly higher when they were based on rate-based methods or calculated on a single season and significantly lower when cases were laboratory-confirmed. The national hospitalisation rates (all ages) varied considerably, ranging from 11.7 (95% CI = 3.8-36.3) per 100 000 in New Zealand to 122.1 (95% CI = 41.5-358.4) per 100 000 in India (all age estimates). Conclusions Using the pooled global influenza-associated hospitalisation rate, we estimate that seasonal influenza epidemics result in 3.2 million cases of severe illness (hospitalisations) per annum. More extensive analyses are required to assess the influence of other factors on the estimates (e.g. vaccination and dominant virus (sub)types) and efforts to harmonize the methods should be encouraged. Our study highlights the high rates of influenza-associated hospitalisations in children aged 0-4 years and the elderly aged 65+ years. [ABSTRACT FROM AUTHOR]

Background: Death certificate data can improve our understanding of the mortality burden associated with respiratory syncytial virus (RSV) and influenza.Methods: We used International Classification of Diseases, Tenth Revision codes listed on death certificates to characterize deaths from 1999 to 2018 as RSV, influenza, and unspecified bronchiolitis. We described the distribution of each cause of death by age, sex, race/ethnicity, place of death, and contributing causes of death.Results: Over the 20-year study period, RSV, bronchiolitis, and influenza were listed as the underlying causes of death on 932, 1046, and 52 293 death certificates, respectively. Children <1 year of age accounted for 39% of RSV and bronchiolitis deaths, while 72% of influenza deaths were in adults ≥65 years. Children <1 year were more likely to die outside of the hospital from RSV, bronchiolitis, or influenza compared to all causes (P < .01), and black infants had the highest mortality rate for all 3 causes. Most infants dying from RSV did not have a high-risk condition listed on the death certificate. Death certificates captured 20%-60% of estimated excess RSV-attributable mortality in infants and <1% in seniors.Conclusions: Thorough reporting on death certificates is an important public health goal, especially as new therapeutics become available. Infants had higher odds of dying out of hospital from respiratory pathogens compared to other causes, and race/ethnicity alone did not explain this disparity. [ABSTRACT FROM AUTHOR]

Background Respiratory syncytial virus (RSV) is a major cause of hospitalizations in young children. We estimated the burden of community-onset RSV-associated hospitalizations among US children aged <2 years by extrapolating rates of RSV-confirmed hospitalizations in 4 surveillance states and using probabilistic multipliers to adjust for ascertainment biases. Methods From October 2014 through April 2015, clinician-ordered RSV tests identified laboratory-confirmed RSV hospitalizations among children aged <2 years at 4 influenza hospitalization surveillance network sites. Surveillance populations were used to estimate age-specific rates of RSV-associated hospitalization, after adjusting for detection probabilities. We extrapolated these rates using US census data. Results We identified 1554 RSV-associated hospitalizations in children aged <2 years. Of these, 27% were admitted to an intensive care unit, 6% needed mechanical ventilation, and 5 died. Most cases (1047/1554; 67%) had no underlying condition. Adjusted age-specific RSV hospitalization rates per 100 000 population were 1970 (95% confidence interval [CI],1787 to 2177), 897 (95% CI, 761 to 1073), 531 (95% CI, 459 to 624), and 358 (95% CI, 317 to 405) for ages 0–2, 3–5, 6–11, and 12–23 months, respectively. Extrapolating to the US population, an estimated 49 509–59 867 community-onset RSV-associated hospitalizations among children aged <2 years occurred during the 2014–2015 season. Conclusions Our findings highlight the importance of RSV as a cause of hospitalization, especially among children aged <2 months. Our approach to estimating RSV-related hospitalizations could be used to provide a US baseline for assessing the impact of future interventions. [ABSTRACT FROM AUTHOR]

Objective. Transcripts from admission chest radiographs could aid in identification of pneumonia cases for public health surveillance. We assessed the reliability of radiographic data abstraction and performance of radiographic key terms to identify pneumonia in patients hospitalized with laboratory-confirmed influenza virus infection. Methods. We used data on patients hospitalized with laboratory-confirmed influenza virus infection from October 2008 through December 2009 from 10 geographically diverse U.S. study sites participating in the Influenza Hospitalization Surveillance Network (FluSurv-NET). Radiographic key terms (i.e., broncho-pneumonia, consolidation, infiltrate, airspace density, and pleural effusion) were abstracted from final impressions of chest radiograph reports. We assessed the reliability of radiographic data abstraction by examining the percent agreement and Cohen's K statistic between clinicians and surveillance staff members. Using a composite reference standard for presence or absence of pneumonia based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes and discharge summary data, we calculated sensitivity, specificity, positive predictive value (PPV), and percent agreement for individual and combined radiographic key terms. Results. For each radiographic key term, the percent agreement between clinicians and surveillance staff members ranged from 89.4% to 98.6% and Cohen's K ranged from 0.46 (moderate) to 0.84 (almost perfect). The combination of bronchopneumonia or consolidation or infiltrate or airspace density terms had sensitivity of 66.5%, specificity of 89.2%, PPV of 80.4%, and percent agreement of 80.1%. Adding pleural effusion did not result in significant changes in sensitivity, specificity, PPV, or percent agreement. Conclusion. Radiographic key terms abstracted by surveillance staff members from final impressions of chest radiograph reports had moderate to almost perfect reliability and could be used to identify pneumonia among patients hospitalized with laboratory-confirmed influenza virus infection. This method can inform pneumonia surveillance and aid in public health response. [ABSTRACT FROM AUTHOR]

Background Little is known about laboratory capacity to routinely diagnose influenza and other respiratory viruses at clinical laboratories and hospitals. Aims We sought to assess diagnostic practices for influenza and other respiratory virus in a survey of hospitals and laboratories participating in the US Influenza Hospitalization Surveillance Network in 2012-2013. Materials and Methods All hospitals and their associated laboratories participating in the Influenza Hospitalization Surveillance Network ( Flu Surv- NET) were included in this evaluation. The network covers more than 80 counties in 15 states, CA, CO, CT, GA, MD, MN, NM, NY, OR, TN, IA, MI, OH, RI, and UT, with a catchment population of ~28 million people. We administered a standardized questionnaire to key personnel, including infection control practitioners and laboratory departments, at each hospital through telephone interviews. Results Of the 240 participating laboratories, 67% relied only on commercially available rapid influenza diagnostic tests to diagnose influenza. Few reported the availability of molecular diagnostic assays for detection of influenza (26%) and other viral pathogens (≤20%) in hospitals and commercial laboratories. Conclusion Reliance on insensitive assays to detect influenza may detract from optimal clinical management of influenza infections in hospitals. [ABSTRACT FROM AUTHOR]

Annual influenza vaccine is recommended for all persons aged ≥6 months in the United States, with recognition that some persons are at risk for more severe disease (1). However, there might be previously unrecognized demographic groups that also experience higher rates of serious influenza-related disease that could benefit from enhanced vaccination efforts. Socioeconomic status (SES) measures that are area-based can be used to define demographic groups when individual SES data are not available (2). Previous surveillance data analyses in limited geographic areas indicated that influenza-related hospitalization incidence was higher for persons residing in census tracts that included a higher percentage of persons living below the federal poverty level (3-5). To determine whether this association occurs elsewhere, influenza hospitalization data collected in 14 FluSurv-NET sites covering 27 million persons during the 2010-11 and 2011-12 influenza seasons were analyzed. The age-adjusted incidence of influenza-related hospitalizations per 100,000 person-years in high poverty (≥20% of persons living below the federal poverty level) census tracts was 21.5 (95% confidence interval [CI]: 20.7-22.4), nearly twice the incidence in low poverty (<5% of persons living below the federal poverty level) census tracts (10.9, 95% CI: 10.3-11.4). This relationship was observed in each surveillance site, among children and adults, and across racial/ethnic groups. These findings suggest that persons living in poorer census tracts should be targeted for enhanced influenza vaccination outreach and clinicians serving these persons should be made aware of current recommendations for use of antiviral agents to treat influenza (6). [ABSTRACT FROM AUTHOR]

Background: Some studies suggest that influenza vaccination might be protective against severe influenza outcomes in vaccinated persons who become infected. We used data from a large surveillance network to further investigate the effect of influenza vaccination on influenza severity in adults aged ≥50 years who were hospitalized with laboratory-confirmed influenza.Methods: We analyzed influenza vaccination and influenza severity using Influenza Hospitalization Surveillance Network (FluSurv-NET) data for the 2012-2013 influenza season. Intensive care unit (ICU) admission, death, diagnosis of pneumonia, and hospital and ICU lengths of stay served as measures of disease severity. Data were analyzed by multivariable logistic regression, parametric survival models, and propensity score matching (PSM).Results: Overall, no differences in severity were observed in the multivariable logistic regression model. Using PSM, adults aged 50-64 years (but not other age groups) who were vaccinated against influenza had a shorter length of ICU stay than those who were unvaccinated (hazard ratio for discharge, 1.84; 95% confidence interval, 1.12-3.01).Conclusions: Our findings show a modest effect of influenza vaccination on disease severity. Analysis of data from seasons with different predominant strains and higher estimates of vaccine effectiveness are needed. [ABSTRACT FROM AUTHOR]

In 2003, surveillance for influenza in hospitalized persons was added to the Centers for Disease Control and Prevention Emerging Infections Program network. This surveillance enabled monitoring of the severity of influenza seasons and provided a platform for addressing priority questions associated with influenza. For enhanced surveillance capacity during the 2009 influenza pandemic, new sites were added to this platform. The combined surveillance platform is called the Influenza Hospitalization Surveillance Network (FluSurv-NET). FluSurv-NET has helped to determine the risk for influenza-associated illness in various segments of the US population, define the severity of influenza seasons and the 2009 pandemic, and guide recommendations for treatment and vaccination programs. [ABSTRACT FROM AUTHOR]

Diagnostic test sensitivity affects rate estimates for laboratory- confirmed influenza-associated hospitalizations. We used data from FluSurv-NET, a national population-based surveillance system for laboratory-confirmed influenza hospitalizations, to capture diagnostic test type by patient age and influenza season. We calculated observed rates by age group and adjusted rates by test sensitivity. Test sensitivity was lowest in adults ≥65 years of age. For all ages, reverse transcription PCR was the most sensitive test, and use increased from <10% during 2003-2008 to ≈70% during 2009-2013. Observed hospitalization rates per 100,000 persons varied by season: 7.3-50.5 for children <18 years of age, 3.0-30.3 for adults 18-64 years, and 13.6-181.8 for adults ≥65 years. After 2009, hospitalization rates adjusted by test sensitivity were ≈15% higher for children <18 years, ≈20% higher for adults 18-64 years, and ≈55% for adults ≥65 years of age. Test sensitivity adjustments improve the accuracy of hospitalization rate estimates. [ABSTRACT FROM AUTHOR]

The article presents an update on influenza activity in the U.S. from September 28, 2014 to February 21, 2015. Topics discussed include an increase in the percentage of specimens that tested positive for influenza based on the findings of World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System laboratories. Information is also presented on novel influenza A viruses that were discovered and antigenic and genetic characterization of influenza viruses.

Annual estimates of the influenza disease burden provide information to evaluate programs and allocate resources. We used a multiplier method with routine population-based surveillance data on influenza hospitalization in the United States to correct for under-reporting and estimate the burden of influenza for seasons after the 2009 pandemic. Five sites of the Influenza Hospitalization Surveillance Network (FluSurv-NET) collected data on the frequency and sensitivity of influenza testing during two seasons to estimate under-detection. Population-based rates of influenza-associated hospitalization and Intensive Care Unit admission from 2010–2013 were extrapolated to the U.S. population from FluSurv-NET and corrected for under-detection. Influenza deaths were calculated using a ratio of deaths to hospitalizations. We estimated that influenza-related hospitalizations were under-detected during 2010-11 by a factor of 2.1 (95%CI 1.7–2.9) for age < 18 years, 3.1 (2.4–4.5) for ages 18-64 years, and 5.2 (95%CI 3.8–8.3) for age 65+. Results were similar in 2011-12. Extrapolated estimates for 3 seasons from 2010–2013 included: 114,192–624,435 hospitalizations, 18,491–95,390 ICU admissions, and 4,915–27,174 deaths per year; 54–70% of hospitalizations and 71–85% of deaths occurred among adults aged 65+. Influenza causes a substantial disease burden in the U.S. that varies by age and season. Periodic estimation of multipliers across multiple sites and age groups improves our understanding of influenza detection in sentinel surveillance systems. Adjusting surveillance data using a multiplier method is a relatively simple means to estimate the impact of influenza and the subsequent value of interventions to prevent influenza. [ABSTRACT FROM AUTHOR]

The article presents a report from the U.S. Centers for Disease Control and Prevention (CDC) on U.S. influenza activity from September 28 to December 6, 2014. Topics discussed include characteristics of influenza virus, antiviral resistance of influenza viruses, and geographical spread of influenza activity in U.S. states. Hospitalizations of adults and children with influenza are also mentioned.

The article explores the 2013-14 influenza season in the U.S., where an increased was seen in November until December, with Influenza A (H1N1)pdm09 viruses predominating overall. Topics discussed include the monitoring conducted by the World Health Organization and National Respiratory and Enteric Virus Surveillance System, the characteristics of 2,905 influenza viruses according to the Centers for Disease Control and Prevention (CDC) and the rate of influenza-related hospitalizations.

Background. Data on the range and severity of influenza-associated complications among children are limited. We describe the frequency and severity of complications in hospitalized children aged <18 years with seasonal influenza (during 2003–2009) and 2009 pandemic influenza A(H1N1) (during 2009–2010).Methods. Population-based surveillance for laboratory-confirmed influenza hospitalizations was conducted among 5.3 million children in 10 states. Complications were identified by International Classification of Diseases, Ninth Revision (ICD-9) codes in medical records.Results. During 2003–2010, 7293 children hospitalized with influenza were identified, of whom 6769 (93%) had complete ICD-9 code data. Among the 6769 children, the median length of hospitalization was 3 days (interquartile range, 2–4 days), 975 (14%) required intensive care, 359 (5%) had respiratory failure, and 40 (1%) died. The most common complications were pneumonia (in 28% of children), asthma exacerbations (in 22% [793/3616] aged ≥2 years), and dehydration (in 21%). Lung abscess/empyema, tracheitis, encephalopathy, bacteremia/sepsis, acute renal failure, and myocarditis were rare (each ≤2% of children) but associated with a median hospitalization duration of ≥6 days, and 48%–70% of children required intensive care. Bacterial cultures with positive results were identified in 2% of children (107/6769); Staphylococcus aureus and Streptococcus pneumoniae were most commonly identified.Conclusions. Complications contribute substantially to the disease burden among children hospitalized with influenza, through intensive care requirements and prolonged hospitalization, highlighting the importance of primary prevention with influenza vaccination. [ABSTRACT FROM AUTHOR]

This article presents information on influenza activity in the U.S. from September 29, 2013 through February 8, 2014. The types of influenza viruses that were detected during this period include influenza A(H1N1) and pdm09(H1N1) viruses, as well as influenza B and A (H3N2) viruses. It discusses the viral surveillance collaboration in the U.S., antigenic characterization and antiviral resistance of influenza viruses.

The article reports on the estimated influenza illnesses and hospitalizations that were averted by influenza vaccination in the U.S. in the 2012-2013 influenza season. A model used by the U.S. Centers for Disease Control and Prevention to estimate outcomes prevented by vaccination is cited. Influenza vaccination resulted in 6.6 million fewer illnesses from October 2012 to May 2013. Vaccination coverage rates were derived from vaccination status according to survey respondents.

The article examines the influenza activity in the U.S. in 2012-2013 and cites recommendations for the components of the Northern Hemosphere influenza vaccine for 2013-2014. Out of the 311,333 specimens tested for influenza viruses, 73,130 were positive from September 30, 2012 to May 18, 2013. The antigenic characterizations of 2,452 influenza viruses collected by the U.S. Centers for Disease Control and Prevention (CDC) since Octiber 2012 are discussed.

Few US studies have assessed racial disparities in viral respiratory hospitalizations among children. This study enrolled black and white children under 5 years of age who were hospitalized for acute respiratory illness (ARI) in 3 US counties during October–May 2002–2009. Population-based rates of hospitalization were calculated by race for ARI and laboratory-confirmed influenza and respiratory syncytial virus (RSV), using US Census denominators. Relative rates of hospitalization between racial groups were estimated. Of 1,415 hospitalized black children and 1,824 hospitalized white children with ARI enrolled in the study, 108 (8%) black children and 111 (6%) white children had influenza and 230 (19%) black children and 441 (29%) white children had RSV. Hospitalization rates were higher among black children than among white children for ARI (relative rate (RR) = 1.7, 95% confidence interval (CI): 1.6, 1.8) and influenza (RR = 2.1, 95% CI: 1.6, 2.9). For RSV, rates were similar among black and white children under age 12 months but higher for black children aged 12 months or more (for ages 12–23 months, RR = 1.7, 95% CI: 1.1, 2.5; for ages 24–59 months, RR = 2.2, 95% CI: 1.3, 3.6). Black children versus white children were significantly more likely to have public insurance or no insurance (85% vs. 43%) and a history of asthma/wheezing (28% vs. 18%) but not more severe illness. The observed racial disparities require further study. [ABSTRACT FROM PUBLISHER]

The article offers information on the U.S. influenza activity from October 2, 2011 to February 11, 2012. During the period, influenza activity remained low, with a slight increased in early February. Viruses identified during the period are influenza A (H1N1) pdm09 (PH1N1), influenza A (H3N3) and influenza B. All 50 states have reported influenza virus-positive test results while the weekly percentage of outpatient visits for influenza-like illness (ILI) ranged from 1.1 percent to 2.1 percent.

Speculation that a universal varicella vaccination program might lead to an increase in herpes zoster (HZ) incidence has been supported by modeling studies that assume that exposure to varicella boosts immunity and protects against reactivation of varicella-zoster virus (VZV) as HZ. Such studies predict an increase in HZ incidence until the adult population becomes predominantly composed of individuals with vaccine-induced immunity who do not harbor wild-type VZV. In the United States, a varicella vaccination program was implemented in 1995. Since then, studies monitoring HZ incidence have shown inconsistent findings: 2 studies have shown no increase in overall incidence, whereas 1 study has shown an increase. Studies from Canada and the United Kingdom have shown increasing rates of HZ incidence in the absence of a varicella vaccination program. Data suggest that heretofore unidentified risk factors for HZ also are changing over time. Further studies are needed to identify these factors, to isolate possible additional effects from a varicella vaccination program. Untangling the contribution of these different factors on HZ epidemiology will be challenging. [ABSTRACT FROM AUTHOR]

Widespread use of varicella vaccine in the United States could enable detection of rare adverse events not identified previously. We reviewed data from 1995 to 2005 from the Vaccine Adverse Event Reporting System, including data from laboratory analyses, to distinguish adverse events associated with wild-type varicella-zoster virus (VZV) versus those associated with vaccine strain. Almost 48 million doses of varicella vaccine were distributed between 1995 and 2005. There were 25,306 adverse events reported (52.7/100,000 doses distributed); 5.0% were classified as serious (2.6/100,000 doses distributed). Adverse events associated with evidence of vaccine-strain VZV included meningitis in patients with concurrent herpes zoster. Patients with genetic predispositions may rarely have disease triggered by receipt of varicella vaccine. Overall, serious adverse events reported after varicella vaccination continue to be rare and must be considered relative to the substantial benefits of varicella vaccination. Ongoing safety surveillance and further studies may shed light on some of the hypothesized associations. [ABSTRACT FROM AUTHOR]

We report detailed population-based data on varicella among adults. In 2 US varicella active surveillance sites with high vaccine coverage among young children, the incidence of varicella among adults declined 74% during 1995-2005. A low proportion (3%) of adults with varicella had been vaccinated, with no improvement over the decade of program implementation, suggesting that the decline was likely secondary to herd-immunity effects. Compared with children, adults had more severe varicella in terms of both clinical presentation and frequency of complications. However, <30% of adults with varicella were treated with acyclovir. Among adolescents, illness severity was intermediate between that in children and adults. Varicella cases are preventable through vaccination. As we enter the second decade of the varicella vaccination program in the United States, we need to ensure that susceptible adolescents and adults are adequately protected from varicella by vaccination and that those who acquire varicella are appropriately treated with effective antiviral treatment. [ABSTRACT FROM AUTHOR]

Significant reductions in varicella incidence were reported from 1995 to 2000 in the varicella active surveillance sites of Antelope Valley (AV), California, and West Philadelphia (WP), Pennsylvania. We examined incidence rates, median age, and vaccination status of case patients for 1995-2005. Coverage data were from the National Immunization Survey. By 2005, coverage among children 19-35 months of age reached 92% (AV) and 94% (WP); 57% and 64% of case patients in AV and WP, respectively, were vaccinated; and varicella incidence declined by 89.8% in AV and 90.4% in WP. Incidence declined in all age groups, especially among children <10 years of age in both sites and among adolescents 10-14 years of age in WP. In AV, since 2000, the incidence among adolescents 10-14 and 15-19 years of age increased. Implementation of school requirements through 10th grade in WP may explain the differences in the decline in incidence among adolescents. Continued surveillance will be important to monitor the impact that the 2-dose vaccine policy in children has on varicella epidemiology. [ABSTRACT FROM AUTHOR]

Two live, attenuated varicella zoster virus-containing vaccines are available in the United States for prevention of varicella: 1) a single-antigen varicella vaccine (VARIVAX,® Merck & Co., Inc., Whitehouse Station, New Jersey), which was licensed in the United States in 1995 for use among healthy children aged ≥ 12 months, adolescents, and adults; and 2) a combination measles, mumps, rubella, and varicella vaccine (ProQuad,® Merck & Co., Inc., Whitehouse Station, New Jersey), which was licensed in the United States in 2005 for use among healthy children aged 12 months-12 years. Initial Advisory Committee on Immunization Practices (ACIP) recommendations for prevention of varicella issued in 1995 (CDC. Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices [ACIP]. MMWR 1996;45[No. RR-11]) included routine vaccination of children aged 12-18 months, catch-up vaccination of susceptible children aged 19 months-12 years, and vaccination of susceptible persons who have close contact with persons at high risk for serious complications (e.g., health-care personnel and family contacts of immunocompromised persons). One dose of vaccine was recommended for children aged 12 months-12 years and 2 doses, 4-8 weeks apart, for persons aged ≥ 13 years. In 1999, ACIP updated the recommendations (CDC. Prevention of varicella: updated recommendations of the Advisory Committee on Immunization Practices [ACIP]. MMWR 1999;48[No. RR-6]) to include establishing child care and school entry requirements, use of the vaccine following exposure and for outbreak control, use of the vaccine for certain children infected with human immunodeficiency virus, and vaccination of adolescents and adults at high risk for exposure or transmission. In June 2005 and June 2006, ACIP adopted new recommendations regarding the use of live, attenuated varicella vaccines for prevention of varicella. This report revises, updates, and replaces the 1996 and 1999 ACIP statements for prevention of varicella. The new recommendations include 1) implementation of a routine 2-dose varicella vaccination program for children, with the first dose administered at age 12-15 months and the second dose at age 4-6 years; 2) a second dose catch-up varicella vaccination for children, adolescents, and adults who previously had received 1 dose; 3) routine vaccination of all healthy persons aged ≥ 13 years without evidence of immunity; 4) prenatal assessment and postpartum vaccination; 5) expanding the use of the varicella vaccine for HIV-infected children with age-specific CD4+T lymphocyte percentages of 15%-24% and adolescents and adults with CD4+T lymphocyte counts ≥ 200 cells/µL; and 6) establishing middle school, high school, and college entry vaccination requirements. ACIP also approved criteria for evidence of immunity to varicella. [ABSTRACT FROM AUTHOR]

Objectives. Exposure to varicella zoster virus through dose contact with people with chickenpox was suggested to boost specific immunity, reducing the risk of herpes zoster (HZ). Since the introduction of the varicella immunization program in the U.S. in 1995, varicella morbidity has decreased substantially. This article examines incidence and risk factors associated with serf-reported HZ disease and whether exposure to chickenpox within the previous decade reduces the risk of shingles in this age group. Methods. In 2004, a national random-digit dial telephone survey was used to obtain information on self-reported HZ disease, demographic characteristics, and exposure to children with chickenpox in the past decade. National estimates of the incidence of shingles disease were calculated. Results. Incidence rate of self-reported HZ was 19 per 1,000 population per year. White individuals were 3.5 times more likely to report shingles than Hispanic individuals (p<0.01). Previous exposure to chickenpox did not protect against HZ disease in this population. Seven percent of adults ≥65 years of age reported exposure to children with chickenpox in the past decade. Conclusions. Incidence of HZ among individuals ≥65 years of age in the U.S. may be higher than previously described in the literature, with whites being at higher risk for the disease. Currently, the potential contribution of exposure to chickenpox as a mechanism for maintaining cell-mediated immunity against HZ may be limited to a small percentage of the population. Vaccination against HZ may represent the best means of decreasing this disease burden. [ABSTRACT FROM AUTHOR]

Abstract: We analysed data from the 2009 National Immunization Survey to determine potential predictors of hepatitis A vaccination coverage among children aged 19–35 months. Overall national coverage was 75% for ≥1 dose. Residence in a state with hepatitis A vaccination recommendations prior to 2006, or in a metropolitan statistical area within such state, or being a minority child were among the variables independently associated with higher vaccination coverage. While hepatitis A vaccination coverage has improved since nationwide routine childhood vaccination began in 2006, coverage remains lower than that for other recommended childhood vaccines. [Copyright &y& Elsevier]

The target populations and financing mechanisms for a new health technology may affect health inequalities in access and impact. We projected the distributional consequences of introducing nirsevimab for prevention of respiratory syncytial virus in a US birth cohort of infants through alternative reimbursement pathway scenarios. Using the RSV immunization impact model, we estimated that a vaccine-like reimbursement pathway would cover 32% more infants than a pharmaceutical pathway. The vaccine pathway would avert 30% more hospitalizations and 39% more emergency room visits overall, and 44% and 44%, respectively, in publicly insured infants. The vaccine pathway would benefit infants from poorer households., Competing Interests: Potential conflicts of interest. G. B. G., C. R., C. B. N., and S. S. C. are employees of Sanofi, a company which makes Nirsevimab, a monoclonal antibody for RSV prevention, and may own Sanofi shares. Sanofi employees were involved in all aspects of data collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication. D. S. S. received grant funding from Sanofi. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization in the United States. Preterm infants and those with select comorbidities are at highest risk of RSV-related complications. However, morbidity due to RSV infection is not confined to high-risk infants. We estimated the burden of medically attended (MA) RSV-associated lower respiratory tract infection (LRTI) among infants in the United States., Methods: We analyzed commercial (MarketScan Commercial [MSC], Optum Clinformatics [OC]), and Medicaid (MarketScan Medicaid [MSM]) insurance claims data for infants born between April 2016 and February 2020. Using both specific and sensitive definitions of MA RSV LRTI, we estimated the burden of MA RSV LRTI during infants' first RSV season, stratified by gestational age, comorbidity status, and highest level of medical care associated with the MA RSV LRTI diagnosis., Results: According to the specific definition 75.0% (MSC), 78.6% (MSM), and 79.6% (OC) of MA RSV LRTI events during infants' first RSV season occurred among term infants without known comorbidities., Conclusions: Term infants without known comorbidities account for up to 80% of the MA RSV LRTI burden in the United States during infants' first RSV season. Future prevention efforts should consider all infants., Competing Interests: Potential conflicts of interest . J. R. G., A. R. Z., and D. A. S. receive research funding support from Sanofi. N. Z. and B. L. are employees of IBM Watson Health, who was contracted by Sanofi to perform analyses included in this paper. S. S. C., W. V. L. V., C. B. N., C. R., and R. vA. are employees of Sanofi. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: Home-based swabbing has not been widely used. The objective of this analysis was to compare respiratory swabs collected by mothers of 7-12-year-olds living in low-income, multilingual communities in the United States with technician collected swabs., Methods: Retrospective data analysis of respiratory samples collected at home by mothers compared to technicians. Anterior nasal and throat specimens collected using flocked swabs were combined in dry tubes. Test was done using TaqMan array cards for viral and bacterial pathogens. Cycle threshold (Ct) values of ribonuclease P (RNP) gene were used to assess specimen quality. Ct < 40 was interpreted as a positive result. Concordance of pathogen yield from mother versus technician collected swabs were analyzed using Cohen's Kappa coefficients. Correlation analysis, paired t-test, and Wilcoxon signed-rank test for paired samples were used for RNP Ct values., Results: We enrolled 36 households in Cincinnati (African American) and 44 (predominately Chinese or Latino) in Boston. In Cincinnati, eight of 32 (25%) mothers did not finish high school, and 11 (34%) had finished high school only. In Boston, 13 of 44 (30%) mothers had less than a high school diploma, 23 (52%) had finished high school only. Mother versus technician paired swabs (n = 62) had similar pathogen yield (paired t-test and Wilcoxon signed rank test p-values = 0.62 and 0.63, respectively; 95% confidence interval of the difference between the two measurements = - 0.45-0.75). Median Ct value for RNP was 22.6 (interquartile range, IQR = 2.04) for mother-collected and 22.4 (IQR = 2.39) for technician-collected swabs (p = 0.62). Agreement on pathogen yield between samples collected by mothers vs. technicians was higher for viruses than for bacterial pathogens, with high concordance for rhinovirus/enterovirus, human metapneumovirus, and adenovirus (Cohen's kappa coefficients ≥80%, p < 0.0001). For bacterial pathogens, concordance was lower to moderate, except for Chlamydia pneumoniae, for which kappa coefficient indicated perfect agreement., Conclusion: Mothers with a range of education levels from low-income communities were able to swab their children equally well as technicians. Home-swabbing using dry tubes, and less invasive collection procedures, could enhance respiratory disease surveillance., (© 2022. The Author(s).)

During the 2014-15 influenza season in the United States, influenza activity increased through late November and December before peaking in late December. Influenza A (H3N2) viruses predominated, and the prevalence of influenza B viruses increased late in the season. This influenza season, similar to previous influenza A (H3N2)-predominant seasons, was moderately severe with overall high levels of outpatient illness and influenza-associated hospitalization, especially for adults aged ≥65 years. The majority of circulating influenza A (H3N2) viruses were different from the influenza A (H3N2) component of the 2014-15 Northern Hemisphere seasonal vaccines, and the predominance of these drifted viruses resulted in reduced vaccine effectiveness. This report summarizes influenza activity in the United States during the 2014-15 influenza season (September 28, 2014-May 23, 2015) and reports the recommendations for the components of the 2015-16 Northern Hemisphere influenza vaccine.

The Advisory Committee on Immunization Practices recommends annual influenza vaccination for all persons aged ≥6 months to reduce morbidity and mortality caused by influenza in the United States. CDC previously developed a model to estimate that annual influenza vaccination resulted in 1.1-6.6 million fewer cases and 7,700-79,000 fewer hospitalizations per season during the 2005-2013 influenza seasons. For the 2013-14 influenza season, using updated estimates of vaccination coverage, vaccine effectiveness, and influenza hospitalizations, CDC estimates that influenza vaccination prevented approximately 7.2 million illnesses, 3.1 million medically attended illnesses, and 90,000 hospitalizations associated with influenza. Similar to prior seasons, fewer than half of persons aged ≥6 months are estimated to have been vaccinated. If influenza vaccination levels had reached the Healthy People 2020 target of 70%, an estimated additional 5.9 million illnesses, 2.3 million medically attended illnesses, and 42,000 hospitalizations associated with influenza might have been averted. For the nation to more fully benefit from influenza vaccines, more effort is needed to reach the Healthy People 2020 target.

Background:  The 2010-2011 influenza season was dominated by influenza A(H3N2) virus, but influenza A(H1N1) pdm09 (pH1N1) and B viruses cocirculated. This provided an opportunity to explore within-season predictors of severity among hospitalized patients, avoiding biases associated with season-to-season differences in strain virulence, population immunity, and healthcare seeking., Methods:  Population-based, laboratory-confirmed influenza hospitalization surveillance data were used to examine the association between virus type/subtype and outcomes in children and adults. Multivariable analysis explored virus type/subtype, prompt antiviral treatment, medical conditions, and age as predictors for severity (intensive care unit admission or death)., Results:  In children, pH1N1 (adjusted odds ratio [aOR], 2.19; 95% confidence interval [CI], 1.11-4.3), chronic metabolic disease (aOR, 5.23; 95% CI, 1.74-15.69), and neuromuscular disorder (aOR, 4.84; 95% CI, 2.02-11.58) were independently associated with severity. In adults, independent predictors were pH1N1 (aOR, 2.21; 95% CI, 1.66-2.94), chronic lung disease (aOR, 1.46, 95% CI, 1.12-1.89), and neuromuscular disorder (aOR, 1.68; 95% CI, 1.11-2.52).Antiviral treatment reduced the odds of severity among adults (aOR, 0.47; 95% CI, .33-.68)., Conclusions:  During the 2010-2011 season, pH1N1 caused more severe disease than H3N2 or B in hospitalized patients. Underlying medical conditions increased severity despite virus strain. Antiviral treatment reduced severity among adults. Our findings underscore the importance of influenza prevention.

Children aged <9 years may require two doses of influenza vaccine to achieve an adequate immune response to protect against the disease. We analyzed data for >2 million children in each influenza season from 2007 to 2012 from eight Immunization Information System Sentinel Sites to assess trends in two-dose compliance. Compliance was calculated by influenza season, age group, and influenza vaccination history. Two-dose compliance increased from 49% to 60% among 6-23 month olds from 2007 to 2012; no increase was observed for 2-4 or 5-8 year olds. In each season, compliance was 3-12 times higher among 6-23 month olds compared to older children and was two times higher among influenza vaccine naïve children compared to previously vaccinated children. Improved messaging for providers and parents about the importance of the two-dose recommendation, about which children are eligible for two doses, and provider access to complete influenza vaccination histories for all children are needed., (Published by Elsevier Ltd.)

Background: Because pneumococcal pneumonia was prevalent during previous influenza pandemics, we evaluated invasive pneumococcal pneumonia (IPP) rates during the 2009 influenza A(H1N1) pandemic., Methods: We identified laboratory-confirmed, influenza-associated hospitalizations and IPP cases (pneumococcus isolated from normally sterile sites with discharge diagnoses of pneumonia) using active, population-based surveillance in the United States. We compared IPP rates during peak pandemic months (April 2009-March 2010) to mean IPP rates in nonpandemic years (April 2004-March 2009) and, using Poisson models, to 2006-2008 influenza seasons., Results: Higher IPP rates occurred during the peak pandemic month compared to nonpandemic periods in 5-24 (IPP rate per 10 million: 48 vs 9 (95% confidence interval [CI], 5-13), 25-49 (74 vs 53 [CI, 41-65]), 50-64 (188 vs 114 [CI, 85-143]), and ≥65-year-olds (229 vs 187 [CI, 159-216]). In the models with seasonal influenza rates included, observed IPP rates during the pandemic peak were within the predicted 95% CIs, suggesting this increase was not greater than observed with seasonal influenza., Conclusions: The recent influenza pandemic likely resulted in an out-of-season IPP peak among persons ≥5 years. The IPP peak's magnitude was similar to that seen during seasonal influenza epidemics.

Objective: To describe varicella disease in infants since implementation of the varicella vaccination program in the United States., Patients and Methods: From 1995 to 2008, demographic, clinical, and epidemiologic data on cases of varicella in infants were collected prospectively through a community-based active surveillance project. We examined disease patterns for infants in 2 age groups: 0 to 5 and 6 to 11 months., Results: Infant varicella disease incidence declined 89.7% from 1995 to 2008. Infants aged 0 to 5 months had milder clinical disease than those aged 6 to 11 months: ≥50 lesions, 49% vs 58% (P = .038); fever (body temperature > 38°C), 12% vs 21% (P = .014); and varicella-related complications, 6% vs 14% (P = .009), respectively. Age was an independent predictor of the occurrence of complications., Conclusions: The varicella vaccination program has resulted in substantial indirect benefits for infants, who are not eligible for vaccination. Presence of maternal varicella-zoster virus antibodies might explain attenuated disease in very young infants likely born to mothers with history of varicella. Although varicella disease incidence has declined, exposure to varicella-zoster virus continues to occur. Improving varicella vaccination coverage in all age groups will further reduce the risk of varicella exposure and protect those not eligible for varicella vaccination.

Background: The introduction of universal varicella vaccination in 1995 has substantially reduced varicella-related morbidity and mortality in the United States. However, it remains unclear whether vaccine-induced immunity wanes over time, a condition that may result in increased susceptibility later in life, when the risk of serious complications may be greater than in childhood., Methods: We examined 10 years (1995 to 2004) of active surveillance data from a sentinel population of 350,000 subjects to determine whether the severity and incidence of breakthrough varicella (with an onset of rash >42 days after vaccination) increased with the time since vaccination. We used multivariate logistic regression to adjust for the year of disease onset (calendar year) and the subject's age at both disease onset and vaccination., Results: A total of 11,356 subjects were reported to have varicella during the surveillance period, of whom 1080 (9.5%) had breakthrough disease. Children between the ages of 8 and 12 years who had been vaccinated at least 5 years previously were significantly more likely to have moderate or severe disease than were those who had been vaccinated less than 5 years previously (risk ratio, 2.6; 95% confidence interval [CI], 1.2 to 5.8). The annual rate of breakthrough varicella significantly increased with the time since vaccination, from 1.6 cases per 1000 person-years (95% CI, 1.2 to 2.0) within 1 year after vaccination to 9.0 per 1000 person-years (95% CI, 6.9 to 11.7) at 5 years and 58.2 per 1000 person-years (95% CI, 36.0 to 94.0) at 9 years., Conclusions: A second dose of varicella vaccine, now recommended for all children, could improve protection from both primary vaccine failure and waning vaccine-induced immunity., (Copyright 2007 Massachusetts Medical Society.)

Efforts to prevent foodborne illness target bacterial pathogens, yet noroviruses (NoV) are suspected to be the most common cause of gastroenteritis. New molecular assays allow for better estimation of the role of NoV in foodborne illness. We analyzed 8,271 foodborne outbreaks reported to the Centers for Disease Control and Prevention from 1991 to 2000 and additional data from 6 states. The proportion of NoV-confirmed outbreaks increased from 1% in 1991 to 12% in 2000. However, from 1998 to 2000, 76% of NoV outbreaks were reported by only 11 states. In 2000, an estimated 50% of foodborne outbreaks in 6 states were attributable to NoV. NoV outbreaks were larger than bacterial outbreaks (median persons affected: 25 versus 15), and 10% of affected persons sought medical care; 1% were hospitalized. More widespread use of molecular assays will permit better estimates of the role of NoV illness and help direct efforts to control foodborne illness.