RSV Vaccine Effectiveness Against Hospitalization Among US Adults Aged 60 Years or Older During 2 Seasons.

Importance: Respiratory syncytial virus (RSV) vaccines for adults aged 60 years or older became available in 2023. One dose is recommended for all adults aged 75 years or older and those aged 60 to 74 years at increased risk of severe RSV; however, duration of protection is unknown.

Objective: To evaluate RSV vaccine effectiveness against RSV-associated hospitalization among adults aged 60 years or older during 2 RSV seasons.

Modeling the Potential Impacts of Outpatient Antiviral Treatment in Reducing Influenza-Associated Hospitalizations in the United States.

Background: Seasonal influenza causes an estimated 120 000 to 710 000 hospitalizations annually in the United States. Treatment with antiviral medications, such as oseltamivir, can reduce risks of hospitalization among people with influenza-associated illness. The US Centers for Disease Control and Prevention recommends initiating antiviral treatment as soon as possible for outpatients with suspected or confirmed influenza who have severe or progressive illness or are at higher risk of influenza complications.

Vaccine Effectiveness Against Influenza A(H1N1), A(H3N2), and B-Associated Hospitalizations-United States, September 1, 2023-May 31, 2024.

Background: The 2023-2024 influenza season included sustained elevated activity from December 2023-February 2024 and continued activity through May 2024. Influenza A(H1N1), A(H3N2), and B viruses circulated during the season.

Methods: During September 1, 2023-May 31, 2024, a multistate sentinel surveillance network of 24 medical centers in 20 U.

Patient- and Community-Level Characteristics Associated With Respiratory Syncytial Virus Vaccination.

Importance: In 2023, the first respiratory syncytial virus (RSV) vaccines were recommended for US adults 60 years or older, but few data are available about which patients were most likely to receive vaccine to inform future RSV vaccine outreach efforts.

Objective: To assess patient- and community-level characteristics associated with RSV vaccine receipt and patient knowledge and attitudes related to RSV disease and RSV vaccines.

Design, Setting, And Participants: During the first season of RSV vaccine use from October 1, 2023, to April 30, 2024, adults 60 years or older hospitalized with RSV-negative acute respiratory illness were enrolled in this cross-sectional study from 26 hospitals in 20 US states.

Interim Estimates of 2024-2025 Seasonal Influenza Vaccine Effectiveness - Four Vaccine Effectiveness Networks, United States, October 2024-February 2025.

Annual influenza vaccination is recommended for all persons aged ≥6 months in the United States. Interim influenza vaccine effectiveness (VE) was calculated among patients with acute respiratory illness-associated outpatient visits and hospitalizations from four VE networks during the 2024-25 influenza season (October 2024-February 2025). Among children and adolescents aged <18 years, VE against any influenza was 32%, 59%, and 60% in the outpatient setting in three networks, and against influenza-associated hospitalization was 63% and 78% in two networks.

Interim Estimates of 2024-2025 COVID-19 Vaccine Effectiveness Among Adults Aged ≥18 Years - VISION and IVY Networks, September 2024-January 2025.

COVID-19 vaccination averted approximately 68,000 hospitalizations during the 2023-24 respiratory season. In June 2024, CDC and the Advisory Committee on Immunization Practices (ACIP) recommended that all persons aged ≥6 months receive a 2024-2025 COVID-19 vaccine, which targets Omicron JN.1 and JN.

Benefit of Early Oseltamivir Therapy for Adults Hospitalized With Influenza A: An Observational Study.

Background: Clinical guidelines recommend initiation of antiviral therapy as soon as possible for patients hospitalized with confirmed or suspected influenza.

Methods: A multicenter US observational sentinel surveillance network prospectively enrolled adults (aged ≥18 years) hospitalized with laboratory-confirmed influenza at 24 hospitals during 1 October 2022-21 July 2023. A multivariable proportional odds model was used to compare peak pulmonary disease severity (no oxygen support, standard supplemental oxygen, high-flow oxygen/non-invasive ventilation, invasive mechanical ventilation, or death) after the day of hospital admission among patients starting oseltamivir treatment on the day of admission (early) versus those who did not (late or not treated), adjusting for baseline (admission day) severity, age, sex, site, and vaccination status.

Assessment and mitigation of bias in influenza and COVID-19 vaccine effectiveness analyses - IVY Network, September 1, 2022-March 30, 2023.

Background: In test-negative studies of vaccine effectiveness (VE), including patients with co-circulating, vaccine-preventable, respiratory pathogens in the control group for the pathogen of interest can introduce a downward bias on VE estimates.

Methods: A multicenter sentinel surveillance network in the US prospectively enrolled adults hospitalized with acute respiratory illness from September 1, 2022-March 31, 2023. We evaluated bias in estimates of VE against influenza-associated and COVID-19-associated hospitalization based on: inclusion vs exclusion of patients with a co-circulating virus among VE controls; observance of VE against the co-circulating virus (rather than the virus of interest), unadjusted and adjusted for vaccination against the virus of interest; and observance of influenza or COVID-19 against a sham outcome of respiratory syncytial virus (RSV).

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.

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%.

Vaccine Effectiveness Against Influenza A-Associated Hospitalization, Organ Failure, and Death: United States, 2022-2023.

Background: Influenza circulation during the 2022-2023 season in the United States largely returned to pre-coronavirus disease 2019 (COVID-19)-pandemic patterns and levels. Influenza A(H3N2) viruses were detected most frequently this season, predominately clade 3C.2a1b.

Epidemiology of SARS-CoV-2 transmission and superspreading in Salt Lake County, Utah, March-May 2020.

Background: Understanding the drivers of SARS-CoV-2 transmission can inform the development of interventions. We evaluated transmission identified by contact tracing investigations between March-May 2020 in Salt Lake County, Utah, to quantify the impact of this intervention and identify risk factors for transmission.

Methods: RT-PCR positive and untested symptomatic contacts were classified as confirmed and probable secondary case-patients, respectively.

Risk factors for infection with influenza A(H3N2) virus on a US university campus, October-November 2021.

Background: Knowledge of the specific dynamics of influenza introduction and spread in university settings is limited.

Methods: Persons with acute respiratory illness symptoms received influenza testing by molecular assay during October 6-November 23, 2022. Viral sequencing and phylogenetic analysis were conducted on nasal swab samples from case-patients.

Absolute and Relative Vaccine Effectiveness of Primary and Booster Series of COVID-19 Vaccines (mRNA and Adenovirus Vector) Against COVID-19 Hospitalizations in the United States, December 2021-April 2022.

Background: Coronavirus disease 2019 (COVID-19) vaccine effectiveness (VE) studies are increasingly reporting relative VE (rVE) comparing a primary series plus booster doses with a primary series only. Interpretation of rVE differs from traditional studies measuring absolute VE (aVE) of a vaccine regimen against an unvaccinated referent group. We estimated aVE and rVE against COVID-19 hospitalization in primary-series plus first-booster recipients of COVID-19 vaccines.

One Health Investigation of SARS-CoV-2 in People and Animals on Multiple Mink Farms in Utah.

From July−November 2020, mink (Neogale vison) on 12 Utah farms experienced an increase in mortality rates due to confirmed SARS-CoV-2 infection. We conducted epidemiologic investigations on six farms to identify the source of virus introduction, track cross-species transmission, and assess viral evolution. Interviews were conducted and specimens were collected from persons living or working on participating farms and from multiple animal species.

Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19-Associated Hospitalization Among Immunocompetent Adults Aged ≥65 Years - IVY Network, 18 States, September 8-November 30, 2022.

Monovalent COVID-19 mRNA vaccines, designed against the ancestral strain of SARS-CoV-2, successfully reduced COVID-19-related morbidity and mortality in the United States and globally (1,2). However, vaccine effectiveness (VE) against COVID-19-associated hospitalization has declined over time, likely related to a combination of factors, including waning immunity and, with the emergence of the Omicron variant and its sublineages, immune evasion (3). To address these factors, on September 1, 2022, the Advisory Committee on Immunization Practices recommended a bivalent COVID-19 mRNA booster (bivalent booster) dose, developed against the spike protein from ancestral SARS-CoV-2 and Omicron BA.

Demographic and Clinical Characteristics of Mpox in Persons Who Had Previously Received 1 Dose of JYNNEOS Vaccine and in Unvaccinated Persons - 29 U.S. Jurisdictions, May 22-September 3, 2022.

As of November 14, 2022, monkeypox (mpox) cases had been reported from more than 110 countries, including 29,133 cases in the United States.* Among U.S.

Reduced Risk for Mpox After Receipt of 1 or 2 Doses of JYNNEOS Vaccine Compared with Risk Among Unvaccinated Persons - 43 U.S. Jurisdictions, July 31-October 1, 2022.

As of October 28, 2022, a total of 28,244* monkeypox (mpox) cases have been reported in the United States during an outbreak that has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (1). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series (with doses administered 4 weeks apart), was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and mpox disease (2); an FDA Emergency Use Authorization issued on August 9, 2022, authorized intradermal administration of 0.