In populations with moderately high background levels of flu vaccination coverage, vaccine intervention programs were found to reduce influenza spread.
A new study by PLOS Medicine found that a city-wide school located influenza vaccine (SLIV) intervention was associated with a decrease in influenza-associated hospitalizations for all age groups and a decrease in school absence rates among students during seasons with an effective influenza vaccine.1
The researchers evaluated a city-wide SLIV intervention that aimed to increase influenza vaccination coverage. The intervention was implemented in approximately 95 preschools and elementary schools in Northern California from 2014 to 2018.2
The objective of the study was to estimate intervention impacts on student influenza vaccination coverage, school absenteeism, and community-wide indirect efforts on laboratory-confirmed influenza hospitalizations, according to the study authors.2
At the beginning of the program, influenza vaccination rates were already more than 50% among elementary school aged children, which was higher than the rates seen at the outset of similar interventions. During the first 2 years of the program, the vaccination efforts had a limited impact; however, during this period, the influenza vaccine that was recommended for children was found to have low efficacy, according to the study authors.1
By the third and fourth years of the program, 2016-2017 and 2017-2018, when the vaccine was found to be more effective, influenza vaccination coverage was 7% and 11% higher among students in the SLIV site, respectively. For pre-program differences in hospitalizations in each area, an increased vaccination rate was associated with a decrease of 17 influenza hospitalizations per 100,000 people among all non-elementary school-aged people in the community in the 2016-2017 school year.1
In the following school year, there were 37 fewer influenza hospitalizations per 100,000 people among non-elementary school-aged people, including 160 fewer influenza hospitalizations per 100,000 people aged 65 years and older. Further, the increased vaccination rates at the SLIV site was also associated with a decrease in illness-related absences per 100 school days during influenza season, according to the study authors.1
The 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 the community, according to the study.2