Effectiveness and coverage of COVID-19 vaccination among the infection-naive population: A community-based retrospective cohort study in China.

INTRODUCTION

The COVID-19 vaccination coverage rate is notably high among the Chinese population; however, as China eased its zero-COVID policy in November 2022, the pandemic outbreak has imposed a substantial burden on Chinese society. This study aims to analyze real-world vaccination effectiveness and waning effects among community-based COVID-19 infection-naive individuals in China and among different sub-groups.

METHODS

An online questionnaire survey was conducted in Beijing, China, from January 13th to February 9th, 2023 and a total of 45,344 eligible respondents were included in the analysis. Vaccination and infection status among different groups classified by age (under 18, 18-59, and over 60) and health conditions (having underlying disease, allergy, cancer, immune deficiency or organ transplant) were analyzed. Propensity score matching and ordered logistic regression were used to examine the effectiveness of different COVID-19 vaccine types, vaccination strategies and the waning effects.

RESULTS

The infection rate was 82.42 % among sampled population. The vaccination rate was 94.70 %, with 23.73 % of them completed primacy vaccination series, 68.54 % completed homogenous booster vaccination and 2.43 % completed heterogenous booster vaccination; however, the high-risk population had a lower vaccination coverage. Results showed that real-world vaccine effectiveness (VE) of homogenous and heterogenous booster vaccination against infection were 11 % and 23 %, respectively, and the elderly benefited the most. Adolescents had a lower booster vaccination coverage and no significant VE was identified. No significant differences were observed among different vaccine types, and waning effects were identified in the booster vaccination group 12 months post-vaccination.

CONCLUSIONS

Low vaccination coverage among high-risk and vulnerable may lead to a huge disease and societal burden, thus improving vaccine coverage of these groups should be prioritized. In addition, due to waning immunity, regular booster vaccination should be scheduled within 12 months.