Timeliness and completeness of serial routine vaccinations among 8062 rural children in southwest China during the COVID-19 pandemic: A multi-stage stratified cluster sampling survey in 1094 villages.

INTRODUCTION

The COVID-19 pandemic disrupted routine vaccination, previous studies had revealed the drop on routine-vaccination coverage in many areas, but no study gave considerable attention to the timeliness and completeness of routine vaccination in rural China at this immunization crisis. This study assessed the timeliness and completeness of serial routine vaccinations among children in rural China, aimed to discover the impact of the pandemic, and provide evidence for further immunization catch-up and supplementary immunization activities.

METHODS

We conducted a multi-stage stratified cluster survey among 8404 children aged 9-48 months in rural Guangxi. We obtained the vaccination status from the child's vaccination certificate and calculated timely vaccination coverage, complete vaccination coverage, timely-and-complete vaccination coverage, and 95 % CI for routine vaccination through weighted estimation analysis. Weighted Kaplan-Meier analyses were applied to estimate the median delay periods, and complete coverage and timely-and-complete coverage for serial vaccines were calculated.

RESULTS

During the COVID-19 pandemic, the overall vaccination coverage for every dose of routine vaccines was over 90 %, but timely vaccination coverage was unsatisfactory (43.86 % for DPT3 and 41.22 % for OPV3). The complete vaccination coverage of multi-dose vaccines was above 90 %, but the timely-and-complete vaccination coverage was lower than 70 %, ranging from the lowest of 32.87 % for DTP1-4 to the highest of 64.34 % for MCV1-2. The median delayed periods for HepB1, OPV2, OPV3, DTP1, DTP2, DTP3, DTP4, and MCV2 were longer than those in the pre-COVID era, especially for HepB1, which extended from 1 to 20 days. The coverage of overall vaccination, timely vaccination, and complete vaccination for children born in 2019 was lower than those in the 2020 and 2021 birth cohorts.

CONCLUSIONS

The timeliness and completeness of vaccination in rural China fell short of expectations during the COVID era. Delayed vaccination remains a significant concern and has been exacerbated during the COVID-19 pandemic.