Photo Credit: Drazen Zigic

The overall efficacy of the influenza vaccine is 55.7% for preventing influenza-related emergency visits or hospitalizations among children of all ages.

The receipt of at least one influenza vaccine dose was estimated to be more than 50% effective in protecting children against influenza-associated emergency department (ED) visits and hospitalizations, according to a study published in JAMA Network Open.

“These findings indicate that it is important for children to receive an annual influenza vaccine to protect against all levels of influenza illness severity, ranging from ED visits to critical hospitalized illness, during the influenza season,” Kelsey M. Sumner, PhD, MSPH, and colleagues wrote.

The case-control study, which used a test-negative design, included 15,728 US children with acute respiratory illness presenting for care at EDs and hospitals across five influenza seasons. The researchers analyzed data for patients aged 6 months through 17 years of age from eight medical centers participating in the New Vaccine Surveillance Network from 2015 to 2020.

Most children in the study (85.5%) were aged from 6 months to 8 years, and 14.5% were aged 9 years and older. About half (49.5%) of all children, regardless of influenza status, were vaccinated.

Vaccine Efficacy Reaches Nearly 60.0%

Among all 15,728 children in the study, 17.2% tested positive and 82.8% tested negative for influenza, according to the findings from Dr. Sumner and colleagues. Among children with positive influenza tests, 61.8% had an ED visit, 33.1% had a non-critical hospitalization, and 5.1% had a critical hospitalization. In total, 138 children were admitted to the intensive care unit; of these, one child required extracorporeal membrane oxygenation use, 35 children were intubated, and two children died.

The overall vaccine effectiveness for preventing influenza-related ED visits or hospitalizations among children of all ages was 55.7%, Dr. Sumner and colleagues estimated. For younger children aged 6 months to 8 years, the estimated vaccine effectiveness was 58.1%. For children aged 9 years and older, it was 42.6%.

Across influenza severity levels, vaccine effectiveness estimates differed little: 52.8% for ED visits, 52.3% for non-critical hospitalizations, and 50.4% for critical hospitalizations.

“Vaccination is one of the most effective ways to protect children against influenza and its complications, including severe illness and hospitalization,” the researchers wrote. “Improving vaccine uptake in children may reduce influenza illness and, subsequently, ED and hospital visits in a time of increased respiratory virus co-circulation.”