ObjectiveTo analyze the epidemiological characteristics of
varicella in Minhang District, Shanghai from 2013 to 2022, and to evaluate the impact of adjusting the
varicella vaccination program to a two-
dose regimen and its inclusion in the Shanghai
immunization program on the
incidence of
varicella. MethodsData on reported
varicella cases from 2013 to 2022 in Minhang District were collected.
Interrupted time series analysis and segmented regression models were used to analyze the changes in
varicella incidence before and after the
adjustment of
varicella immunization strategies. ResultsFrom 2013 to 2022, the average annual
incidence of
varicella was 76.58/100 000, with the highest
incidence in 2017 (119.21/100 000) and the lowest in 2022 (27.02/100 000). The
varicella incidence exhibited seasonal patterns with peaks occurring from March to June and October to January of the following year. Prior to the
adjustment of
varicella immunization strategies (2013‒2017), the
varicella incidence showed an upward trend (z=2.20, P=0.03), while after the
adjustment (2018‒2022), a adownward trend was observed (2018‒2022) (z=-2.25, P=0.02).
Interrupted time series analysis showed that following the
adjustment of
varicella immunization strategies, an immediate change of -33.91/100 000 (t=-4.35, P<0.001) in
varicella incidence was observed, and the
incidence slope was -17.59/100 000 with a decline of 28.61/100 000 (t=-12.16, P<0.001) compared to before inclusion. ConclusionThe
incidence of
varicella in Minhang District, Shanghai from 2013 to 2022 exhibits distinct seasonal patterns. After adjusting the
varicella vaccination program to a two-
dose regimen and incorporating it into the
immunization program, the second
dose of
varicella vaccine administration substantially increases. As a result, the rising trend of
varicella incidence is effectively controlled, and the
incidence level decreases significantly, showing a sustained downward trend.