The global prevalence of enterovirus A71 (EV-A71)-associated hand, foot, and mouth disease (HFMD) has been documented, with patients, families, and society in China bearing a disproportionate share of the burden. Three Chinese firms have licensed inactivated EV-A71 vaccines, all of which have shown high effectiveness in clinical studies for preventing EV-A71-associated illness. However, the EV-A71 vaccine’s real-world performance has yet to be determined. To assess vaccination efficacy (VE) against medically attended EV-A71-associated HFMD, researchers utilized a test-negative design case-control research. Children aged 5 and under who had been at health institutions participating in the HFMD case and virologic surveillance platforms in Beijing were the subjects. Laboratory confirmation of enterovirus infections was obtained, and EV-A71 vaccination status was retrieved from computerized immunization data. Cases were children who tested positive for EV-A71 infection, whereas controls were children who tested negative for EV-A71 infection. VE was calculated using logistic regression. By repeating the regression analysis with two different control groups, they evaluated the sensitivity of VE estimations to control group inclusion criteria. The researchers recruited a total of 2,184 HFMD patients aged 5 and younger; 24 were severe and 2,160 were mild. The two-dose VE estimate for severe patients was 100 percent. The 1-dose and 2-dose adjusted VE estimates for moderate cases were 69.8 percent and 83.7 percent, respectively. Regardless of the control group definition, two-dose VE estimations differed by less than 4 percentage points.

The data indicated that the vaccinations worked effectively in the actual world for children aged 5 and younger in Beijing, China.