On Dec. 30, 2024, a study published in JAMA Network Open found that the estimated effectiveness of at least one dose of the influenza vaccine against emergency department (ED) visits or hospitalization was over 50% across disease severity levels among nearly 16,000 US children during five respiratory illness seasons.

The New Vaccine Surveillance Network Collaborators conducted a case-control study with a test-negative design with 15,728 children aged 6 months to 17 years who visited an ED or were hospitalized at one of eight US medical centers for acute respiratory illness from November 2015 to April 2020. 

In total, 17.2% of participants tested positive for flu, and 82.8% tested negative and served as controls. Of flu patients, 61.8% visited an ED, 33.1% were hospitalized for noncritical disease, and 5.1% were hospitalized for critical illness, including 138 children admitted to an intensive care unit (ICU), 1 who required extracorporeal membrane oxygenation (ECMO), 35 who were intubated, and 2 who died. The team noted that uptake of other childhood vaccines such as those against pertussis (whooping cough) rose after published studies estimated high VE against severe illness.