Upgrading the school entry vaccination record check strategy to improve varicella vaccination coverage: results from a quasi-experiment study.

Background: The school entry vaccination record check strategy (SECS) is an appropriate opportunity to recommend vaccines for students to improve vaccination coverage (VC). However, it is only utilized for providing necessary catch-up vaccination for students who are missing the Expanded Program on Immunization (EPI) vaccines in China. We aimed to address that gap and quantify the relationship between the SECS policy and the increase of coverage in varicella vaccine (VarV).Methods: We employed a pretest and posttest quasi-experimental design to examine the effect of the upgraded SECS policy on the change of VarV coverage in newly enrolled students in Lu'an, 2019-2020.Results: Eight hundred participants were randomly divided into the control group (C group, 31.8%), the telephone-based intervention group (T group, 31.2%), and the written notification intervention group (W group, 37.0%). Totally, 84 students received VarV during the study period, with a VC of 10.5%. The possibility of vaccination in the T group (RR = 4.9, 95% CI:2.2-10.9) and W group (RR = 5.2, 95% CI:2.4-11.5) was significantly higher than that in the C group (p< .001).Conclusions: Our study demonstrates that the upgraded SECS produce a positive effect on improving the VC of VarV. This nudge strategy may decrease varicella outbreaks in schools in China, especially in provinces where VarV is not introduced into EPI.