Document Type

Article

Publication Date

12-2-2024

Identifier

DOI: 10.1001/jamanetworkopen.2024.52512; PMCID: PMC11681373

Abstract

IMPORTANCE: Increasing the understanding of vaccine effectiveness (VE) against levels of severe influenza in children could help increase uptake of influenza vaccination and strengthen vaccine policies globally.

OBJECTIVE: To investigate VE in children by severity of influenza illness.

DESIGN, SETTING, AND PARTICIPANTS: This case-control study with a test-negative design used data from 8 participating medical centers located in geographically different US states in the New Vaccine Surveillance Network from November 6, 2015, through April 8, 2020. Participants included children 6 months through 17 years of age who were hospitalized or presented to an emergency department (ED) with acute respiratory illness.

EXPOSURES: Receipt of at least 1 dose of the current season's influenza vaccine.

MAIN OUTCOMES AND MEASURES: Demographic and clinical characteristics of patients presenting to the hospital or ED with or without influenza were recorded and grouped by influenza vaccination status. Estimated VE against severe influenza illness was calculated using multiple measures to capture illness severity. Data were analyzed between June 1, 2022, and September 30, 2023.

RESULTS: Among 15 728 children presenting for care with acute respiratory illness (8708 [55.4%] male; 13 450 [85.5%] 6 months to 8 years of age and 2278 [14.5%] 9-17 years of age), 2710 (17.2%) had positive influenza tests and 13 018 (82.8%) had negative influenza tests (controls). Of the influenza test-positive cases, 1676 children (61.8%) had an ED visit, 896 children (33.1%) required hospitalization for noncritical influenza, and 138 children (5.1%) required hospitalization for critical influenza. About half (7779 [49.5%]) of the children (both influenza test positive and test negative) were vaccinated. Receiving at least 1 influenza vaccine dose was estimated to have a VE of 55.7% (95% CI, 51.6%-59.6%) for preventing influenza-associated ED visits or hospitalizations among children of all ages. The estimated VE was similar across severity levels: 52.8% (95% CI, 46.6%-58.3%) for ED visits, 52.3% (95% CI, 44.8%-58.8%) for noncritical hospitalization, and 50.4% (95% CI, 29.7%-65.3%) for critical hospitalization.

CONCLUSIONS AND RELEVANCE: Findings from this case-control study with a test-negative design involving children with a spectrum of influenza severity suggest that influenza vaccination protects children against all levels of severe influenza illness.

Journal Title

JAMA Netw Open

Volume

7

Issue

12

First Page

2452512

Last Page

2452512

MeSH Keywords

Humans; Influenza, Human; Child; Child, Preschool; Male; Female; Influenza Vaccines; Case-Control Studies; Adolescent; Infant; Vaccine Efficacy; United States; Severity of Illness Index; Hospitalization; Vaccination; Emergency Service, Hospital

PubMed ID

39729317

Keywords

Human Influenza; Influenza Vaccines; Case-Control Studies; Vaccine Efficacy; United States; Severity of Illness Index; Hospitalization; Vaccination; Hospital Emergency Service

Comments

Some authors are federal employees of the US government, and this work was prepared as part of their official duties. Title 17 U.S.C. 105 provides that “copyright protection under this title is not available for any work of the US government.”

This is an open access article distributed under the terms of the CC-BY License.

Publisher's Link: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2828501

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