Study: School Flu Vaccine Program Impacts Community-Wide Influenza Hospitalizations

August 24, 2020

A school flu vaccine program resulted in decreased influenza hospitalizations for all age groups and fewer illness-related school absences, suggesting herd immunity.

A community-wide school influenza vaccine intervention program was associated with reduced flu hospitalizations for all age groups, as well as decreased rates of school absences among students in seasons with an effective influenza vaccine, according to a new study.1

The study, published in PLOS Medicine, took place in northern California from 2014 to 2018 in 95 preschools and elementary schools. Study investigators implemented a matched cohort design to identify a nearby comparison school district with similar pre-intervention characteristics.2

The investigators cited previous mathematical models that estimated that vaccinating at least 80% of school-aged children, who are responsible for the majority of influenza transmission, significantly boosts herd immunity and may lead to community-wide reduction in transmission.2

The school-located influenza vaccination (SLIV) program took place largely in an urban and predominantly low-income city; the median household income was $51,849 in the intervention site and $61,596 in the comparison site. Forty-one percent of the population at the intervention site was white and 26% was Hispanic or Latino; 48% of the population at the comparison site was white, and 33% was Hispanic or Latino, according to investigators.2

Investigators determined that by the third and fourth years of the program, influenza vaccination coverage was 7 to 11% higher among students in the SLIV site versus the comparison site.2

The influenza program was linked to significantly lower influenza hospitalization rates among non-elementary-school-aged individuals in the community and among the elderly, suggesting herd immunity effects.2 The 2016-2017 school year revealed a decrease of 17 influenza hospitalizations per 100,000 individuals not of elementary school age in the city. The 2017-2018 school year displayed 37 fewer hospitalizations per 100,000 individuals of the same demographic.1,2

Not only that, but the results also showed that among community members aged 65 and older, there were 160 fewer influenza hospitalizations per 100,000. 1,2

Additionally, the study reported fewer absences due to illness in the SLIV district versus the comparison district within the 4-year time frame.2

"Our findings suggest that in populations with moderately high background levels of influenza vaccination coverage, SLIV programs are associated with further increases in coverage and reduced influenza across communities," the authors said.1


  1. PLOS. School flu vaccine program reduces community-wide influenza hospitalizations. ScienceDaily. August 18, 2020. Accessed August 24, 2020.
  2. Benjamin-Chung J, Arnold BF, Kennedy CJ, et al. Evaluation of a city-wide school-located influenza vaccination program in Oakland, California, with respect to vaccination coverages, school absences, and laboratory-confirmed influenza: A matched cohort study. PLOS Medicine. 2020; doi: