Effectiveness of the influenza vaccine for preventing laboratory-confirmed influenza infections in outpatient immunocompromised adults, 2017-2018.

While the number of immunocompromised (IC) individuals continues to rise, the existing literature on influenza vaccine effectiveness (VE) in IC populations is limited. Understanding the vaccine effectiveness (VE) of the seasonal influenza vaccines in immunocompromised (IC) populations remains paramount. Using 2017-2018 US Flu VE Network data, we examined the VE of the 2017-2018 seasonal influenza vaccine against symptomatic influenza in outpatient settings among IC adults.

In depth sequencing of a serially sampled household cohort reveals the within-host dynamics of Omicron SARS-CoV-2 and rare selection of novel spike variants.

SARS-CoV-2 has undergone repeated and rapid evolution to circumvent host immunity. However, outside of prolonged infections in immunocompromised hosts, within-host positive selection has rarely been detected. The low diversity within-hosts and strong genetic linkage among genomic sites make accurately detecting positive selection difficult.

Influenza vaccine effectiveness against medically attended outpatient illness, United States, 2023-24 season.

Background: The 2023-24 U.S. influenza season was characterized by a predominance of A(H1N1)pdm09 virus circulation with co-circulation of A(H3N2) and B/Victoria viruses.

Influenza A virus within-host evolution and positive selection in a densely sampled household cohort over three seasons.

While influenza A virus (IAV) antigenic drift has been documented globally, in experimental animal infections, and in immunocompromised hosts, positive selection has generally not been detected in acute infections. This is likely due to challenges in distinguishing selected rare mutations from sequencing error, a reliance on cross-sectional sampling, and/or the lack of formal tests of selection for individual sites. Here, we sequenced IAV populations from 346 serial, daily nasal swabs from 143 individuals collected over three influenza seasons in a household cohort.

Randomised immunogenicity trial comparing 2019-2020 recombinant and egg-based influenza vaccines among frequently vaccinated healthcare personnel in Israel.

Objectives: Trivalent inactivated influenza vaccine effectiveness was low in a prospective cohort of healthcare personnel (HCP) in Israel from 2016 to 2019. We conducted a randomised immunogenicity trial of quadrivalent recombinant influenza vaccine (RIV4) and standard-dose inactivated influenza vaccine (IIV4) among frequently and infrequently vaccinated previous cohort participants.

Methods: From October 2019 to January 2020, we enrolled and randomly allocated HCP from two Israeli hospitals to receive IIV4 or RIV4.

Respiratory Viral Infections from 2015 to 2022 in the HIVE Cohort of American Households: Incidence, illness characteristics, and seasonality.

Background: Viral respiratory illnesses are the most common acute illnesses experienced and generally follow a predicted pattern over time. The SARS-CoV-2 pandemic interrupted that pattern.

Methods: The HIVE (Household Influenza Vaccine Evaluation) study was established in 2010 to follow a cohort of Southeast Michigan households over time.

Incidence of laboratory-confirmed influenza and RSV and associated presenteeism and absenteeism among healthcare personnel, Israel, influenza seasons 2016 to 2019.

BackgroundHealthcare personnel (HCP) are at high risk for respiratory infections through occupational exposure to respiratory viruses.AimWe used data from a prospective influenza vaccine effectiveness study in HCP to quantify the incidence of acute respiratory infections (ARI) and their associated presenteeism and absenteeism.MethodsAt the start and end of each season, HCP at two Israeli hospitals provided serum to screen for antibodies to influenza virus using the haemagglutination inhibition assay.

Transfer of Respiratory Syncytial Virus Prefusion F Protein Antibody in Low Birthweight Infants.

Background: Respiratory syncytial virus (RSV)-associated lower respiratory tract infection contributes significantly to morbidity/mortality worldwide in low birthweight (LBW) infants (<2500 g). Studies have demonstrated decreased maternal immunoglobulin G (IgG) transfer of various antibodies to LBW infants. We aimed to evaluate naturally acquired RSV anti-prefusion F protein (anti-preF) antibody transfer in pregnancies with LBW versus normal birthweight (NBW) infants.

Antibody Response to Symptomatic Infection With SARS-CoV-2 Omicron Variant Viruses, December 2021-June 2022.

We describe humoral immune responses in 105 ambulatory patients with laboratory-confirmed SARS-CoV-2 Omicron variant infection. In dried blood spot (DBS) collected within 5 days of illness onset and during convalescence, we measured binding antibody (bAb) against ancestral spike protein receptor binding domain (RBD) and nucleocapsid (N) protein using a commercial multiplex bead assay. Geometric mean bAb concentrations against RBD increased by a factor of 2.

Late-Season Influenza Vaccine Effectiveness Against Medically Attended Outpatient Illness, United States, December 2022-April 2023.

Background: The 2022-23 US influenza season peaked early in fall 2022.

Methods: Late-season influenza vaccine effectiveness (VE) against outpatient, laboratory-confirmed influenza was calculated among participants of the US Influenza VE Network using a test-negative design.

Results: Of 2561 participants enrolled from December 12, 2022 to April 30, 2023, 91 laboratory-confirmed influenza cases primarily had A(H1N1)pdm09 (6B.

Effectiveness of Updated 2023-2024 (Monovalent XBB.1.5) COVID-19 Vaccination Against SARS-CoV-2 Omicron XBB and BA.2.86/JN.1 Lineage Hospitalization and a Comparison of Clinical Severity - IVY Network, 26 Hospitals, October 18, 2023-March 9, 2024.

Background: Assessing COVID-19 vaccine effectiveness (VE) and severity of SARS-CoV-2 variants can inform public health risk assessments and decisions about vaccine composition. BA.2.

Reduced Effectiveness of Repeat Influenza Vaccination: Distinguishing Among Within-Season Waning, Recent Clinical Infection, and Subclinical Infection.

Studies have reported that prior-season influenza vaccination is associated with higher risk of clinical influenza infection among vaccinees. This effect might arise from incomplete consideration of within-season waning and recent infection. Using data from the US Flu Vaccine Effectiveness Network (2011-2012 to 2018-2019 seasons), we found that repeat vaccinees were vaccinated earlier in a season by 1 week.

Severity of Respiratory Syncytial Virus vs COVID-19 and Influenza Among Hospitalized US Adults.

Importance: On June 21, 2023, the Centers for Disease Control and Prevention recommended the first respiratory syncytial virus (RSV) vaccines for adults aged 60 years and older using shared clinical decision-making. Understanding the severity of RSV disease in adults can help guide this clinical decision-making.

Objective: To describe disease severity among adults hospitalized with RSV and compare it with the severity of COVID-19 and influenza disease by vaccination status.

Interim Estimates of 2023-24 Seasonal Influenza Vaccine Effectiveness - United States.

In the United States, annual influenza vaccination is recommended for all persons aged ≥6 months. Using data from four vaccine effectiveness (VE) networks during the 2023-24 influenza season, interim influenza VE was estimated among patients aged ≥6 months with acute respiratory illness-associated medical encounters using a test-negative case-control study design. Among children and adolescents aged 6 months-17 years, VE against influenza-associated outpatient visits ranged from 59% to 67% and against influenza-associated hospitalization ranged from 52% to 61%.