For the study, the researchers wanted to assess the coverage, completeness, and timeliness of regular vaccinations among children aged 1 to 7 years in Zhejiang province.
On December 31, 2017, demographic information and vaccination data for 4,613,160 children born between January 1, 2010, and December 31, 2016, were collected from the Zhejiang provincial immunization information system (ZJIIS). Vaccination coverage for each vaccine dose, as well as the completeness of various vaccination series, were determined based on birth cohort, immigrant status, and geographic location. The timeliness of vaccination doses planned before the age of 12 months for the 2016 birth cohort was also investigated.
The coverage of all vaccination doses planned before the age of 12 as well as its completeness, met the objective of 90%. The coverage and completeness of immunizations planned after 12 months of age declined significantly, with the majority of them falling below 90%. Migrant children had poorer coverage and timeliness estimates than resident children, while Wenzhou (WZ), Zhoushan (ZS), and Lishui (LS) had worse coverage across all birth cohorts than other cities.
Despite good coverage rates for all antigens by 12 months, there was a wide range of percent vaccination delay when comparing various antigens scheduled in the first year of life for the 2016 birth cohort.