Objective To evaluate the protective effectiveness (VE) of acellular pertussis vaccine (aPV) in children ≤10 years of age in Nanshan district, Shenzhen city, Guangdong province, and to provide a reference for optimizing pertussis immunization strategies.

Methods A 1:1 matched case-control study was conducted. A total of 442 clinically diagnosed or confirmed pertussis cases aged 4 months to 10 years reported in Nanshan district, Shenzhen city, from January 1, 2023, to March 25, 2024, were selected as the case group from the Chinese Center for Disease Control and Prevention Information System. A total of 442 healthy children with no history of pertussis infection, matched by residential community, sex, and birth date (±1 month), were selected as the control group from the Shenzhen Immunization Program Information Management System. Data on aPV immunization history were collected for both groups. A binary conditional logistic regression model was used to analyze the VE of aPV.

Results The aPV vaccination rates in the case and control groups of children ≤10 years of age in Nanshan district, Shenzhen city were 94.3% (417/442) and 99.1% (438/442), respectively. The overall VE of aPV against pertussis was 84.8% (95%CI: 55.9%–94.7%). The VE of 1–2, 3, and 4 doses of aPV against pertussis was 82.5% (95%CI: 33.6%–95.4%), 88.6% (95%CI: 64.6%–96.3%), and 84.3% (95%CI: 54.3%–94.6%), respectively. The VE of 4 doses of whole-cell aPV, 1–3 doses of component pertussis vaccine plus 1–3 doses of whole-cell aPV, and 4 doses of component pertussis vaccine against pertussis was 80.5% (95%CI: 43.1%–93.3%), 91.3% (95%CI: 71.0%–97.4%), and 89.6% (95%CI: 68.8%–96.5%), respectively. The VE of aPV 0–2, 3–6, and 7–9 years after completion of the full vaccination schedule was 87.0% (95%CI: 60.6%–95.7%), 83.8% (95%CI: 52.8%–94.4%), and 82.5% (95%CI: 46.7%–94.3%), respectively. The VE of component pertussis vaccine 0–2, 3–6, and 7–9 years after completion of the full vaccination schedule was 87.7% (95%CI: 61.3%–96.1%), 89.9% (95%CI: 68.5%–96.8%), and 92.9% (95%CI: 72.7%–98.1%), respectively. The VE of whole-cell aPV 0–2, 3–6, and 7–9 years after completion of the full vaccination schedule was 85.3% (95%CI: 51.2%–95.6%), 80.1% (95%CI: 41.7%–93.2%), and 78.8% (95%CI: 33.8%–93.2%), respectively.

Conclusions Timely and full aPV immunization can effectively prevent pertussis in children ≤10 years of age. It is recommended to develop component pertussis-containing combination vaccines for basic immunization.