Effectiveness of Influenza Vaccination in Preventing Hospitalization Due to Influenza in Children: A Systematic Review and Meta-analysis

This systematic review assesses the literature for estimates of influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalization in children. Studies of any design to June 8, 2020, were included if the outcome was hospitalization, participants were 17 years or younger and influenza infection was laboratory-confirmed. A random-effects meta-analysis of 37 studies that used a test-negative design gave a pooled seasonal IVE against hospitalization of 53.3% (47.2-58.8) for any influenza. IVE was higher against influenza A/H1N1pdm09 (68.7%, 56.9-77.2) and lowest against influenza A/H3N2 (35.8%, 23.4-46.3). Estimates by vaccine type ranged from 44.3% (30.1-55.7) for live-attenuated influenza vaccines to 68.9% (53.6-79.2) for inactivated vaccines. IVE estimates were higher in seasons when the circulating influenza strains were antigenically matched to vaccine strains (59.3%, 48.3-68.0). Influenza vaccination gives moderate overall protection against influenza-associated hospitalization in children supporting annual vaccination. IVE varies by influenza subtype and vaccine type.

Automated summary

This systematic review found that the effectiveness of influenza vaccine against hospitalization in children varies by influenza subtype and vaccine type, with an overall seasonal IVE of 53.3%. IVE was highest against influenza A/H1N1pdm09 and lowest against influenza A/H3N2.