Dataset Information

Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study.

ABSTRACT:

Background

Influenza vaccine effectiveness (VE) against a spectrum of severe disease, including critical illness and death, remains poorly characterized.

Methods

We conducted a test-negative study in an intensive care unit (ICU) network at 10 US hospitals to evaluate VE for preventing influenza-associated severe acute respiratory infection (SARI) during the 2019-2020 season, which was characterized by circulation of drifted A/H1N1 and B-lineage viruses. Cases were adults hospitalized in the ICU and a targeted number outside the ICU (to capture a spectrum of severity) with laboratory-confirmed, influenza-associated SARI. Test-negative controls were frequency-matched based on hospital, timing of admission, and care location (ICU vs non-ICU). Estimates were adjusted for age, comorbidities, and other confounders.

Results

Among 638 patients, the median (interquartile) age was 57 (44-68) years; 286 (44.8%) patients were treated in the ICU and 42 (6.6%) died during hospitalization. Forty-five percent of cases and 61% of controls were vaccinated, which resulted in an overall VE of 32% (95% CI: 2-53%), including 28% (-9% to 52%) against influenza A and 52% (13-74%) against influenza B. VE was higher in adults 18-49 years old (62%; 95% CI: 27-81%) than those aged 50-64 years (20%; -48% to 57%) and ≥65 years old (-3%; 95% CI: -97% to 46%) (P = .0789 for interaction). VE was significantly higher against influenza-associated death (80%; 95% CI: 4-96%) than nonfatal influenza illness.

Conclusions

During a season with drifted viruses, vaccination reduced severe influenza-associated illness among adults by 32%. VE was high among young adults.

SUBMITTER: Grijalva CG

PROVIDER: S-EPMC8682606 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature

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Publications

Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study.

Grijalva Carlos G CG Feldstein Leora R LR Talbot H Keipp HK Aboodi Michael M Baughman Adrienne H AH Brown Samuel M SM Casey Jonathan D JD Erickson Heidi L HL Exline Matthew C MC Files D Clark DC Gibbs Kevin W KW Ginde Adit A AA Gong Michelle N MN Halasa Natasha N Khan Akram A Lindsell Christopher J CJ Nwosu Samuel K SK Peltan Ithan D ID Prekker Matthew E ME Rice Todd W TW Shapiro Nathan I NI Steingrub Jay S JS Stubblefield William B WB Tenforde Mark W MW Patel Manish M MM Self Wesley H WH

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20211001 8

<h4>Background</h4>Influenza vaccine effectiveness (VE) against a spectrum of severe disease, including critical illness and death, remains poorly characterized.<h4>Methods</h4>We conducted a test-negative study in an intensive care unit (ICU) network at 10 US hospitals to evaluate VE for preventing influenza-associated severe acute respiratory infection (SARI) during the 2019-2020 season, which was characterized by circulation of drifted A/H1N1 and B-lineage viruses. Cases were adults hospitali ...[more]

PMID: 34014274

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Project description:BackgroundAnnual estimates of seasonal influenza vaccine effectiveness can guide global risk communication and vaccination strategies to mitigate influenza-associated illness. We aimed to evaluate vaccine effectiveness in countries using the 2023 southern hemisphere influenza vaccine formulation.MethodsWe evaluated end-of-season influenza vaccine effectiveness across eight countries (Argentina, Australia, Brazil, Chile, New Zealand, Paraguay, Thailand, and Uruguay) that used the 2023 southern hemisphere vaccine formulation, with use of a test-negative design. All patients who attended participating hospitals with severe acute respiratory illness were tested by RT-PCR for influenza. We calculated country-specific, network-specific, and pooled vaccine effectiveness against hospitalisation. For countries with sufficient data, we also calculated vaccine effectiveness against intensive care unit (ICU) admission by comparing the odds of vaccination among test-positive cases to that among test-negative controls. We evaluated vaccine effectiveness for groups prioritised for vaccination (young children aged 1-4 years, people aged 5-64 years with underlying health conditions, and older adults aged ≥65 years).FindingsFrom March 5 to Nov 27, 2023, 31 368 individuals were admitted to hospital with severe acute respiratory infection in the eight included countries. Of these, 12 609 individuals admitted to hospital (6452 [51·2%] female and 6157 [48·8%] male) who met inclusion criteria and had complete data were included in the analysis, including 4388 test-positive cases and 8221 test-negative controls. Pooled vaccine effectiveness against hospitalisation with any influenza virus was 51·9% (95% CI 37·2-66·7), with substantial heterogeneity across countries (I2 74%). Vaccine effectiveness against ICU admission from any influenza virus was 67·7% (44·5-81·2) in Chile and 69·7% (45·3-83·3) in Australia. Vaccine effectiveness estimates against hospitalisation were highest for young children (70·9% [47·5-94·4]) and lowest for older adults (47·7% [24·9-70·5]).InterpretationAcross eight countries, 2023 southern hemisphere vaccines were effective in reducing hospitalisations from influenza illness. Use of common protocols can facilitate data pooling to provide a comprehensive evaluation of vaccine effectiveness across settings.FundingUS Centers for Disease Control and Prevention cooperative agreements to the Pan American Health Organization and the Thailand Ministry of Public Health; the Australian Government Department of Health and Aged Care; and the New Zealand Ministry of Health.

Project description:This report updates the 2019-20 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2019;68[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ?6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. Most influenza vaccines available for the 2020-21 season will be quadrivalent, with the exception of MF59-adjuvanted IIV, which is expected to be available in both quadrivalent and trivalent formulations.Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 23, 2019; February 26, 2020; and June 24, 2020. Primary updates to this report include the following two items. First, the composition of 2020-21 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B/Victoria lineage components. Second, recent licensures of two new influenza vaccines, Fluzone High-Dose Quadrivalent and Fluad Quadrivalent, are discussed. Both new vaccines are licensed for persons aged ?65 years. Additional changes include updated discussion of contraindications and precautions to influenza vaccination and the accompanying Table, updated discussion concerning use of LAIV4 in the setting of influenza antiviral medication use, and updated recommendations concerning vaccination of persons with egg allergy who receive either cell culture-based IIV4 (ccIIV4) or RIV4.The 2020-21 influenza season will coincide with the continued or recurrent circulation of SARS-CoV-2 (the novel coronavirus associated with coronavirus disease 2019 [COVID-19]). Influenza vaccination of persons aged ?6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient illnesses, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html.This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2020-21 season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration (FDA)-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information.

Dataset Information

Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study.

Background

Methods

Results

Conclusions

Publications

Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study.

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