Underestimated Incidence Rate of Pertussis in the Community: Results from Active Population-Based Surveillance in Yiwu, China.

BACKGROUND

The resurgence of pertussis in China underscores the urgency of active surveillance to complement the passive surveillance system.

METHODS

Active surveillance for pertussis was conducted from 1 June 2021 to 31 May 2022, at Yiwu, Zhejiang province of China. Patients with suspected pertussis were further confirmed as pertussis cases by PCR and culture. The incidence rate of pertussis in the community was estimated.

RESULTS

The overall estimated incidence of pertussis was 108.3 per 100,000 (95% CrI: 91.7-126.4). Children aged 4-5 years had the highest incidence (1154.3 per 100,000 [95% CrI: 817.4-1553.5]), followed by infants aged 1 year (836.1 per 100,000 [95% CrI: 434.0-1308.8]). Infants aged 0-4 months had the highest hospitalization rate among the pertussis patients (>50.0%). Although the incidence was low in elderly aged ≥ 60 years, the hospitalization rate was rather high (6.7%).

CONCLUSION

Active surveillance in this study revealed a higher burden of pertussis in Yiwu, China, compared to passive surveillance. Children aged 4-5 years are the dominant population group at risk of pertussis. Infants aged ≤ 4 months are the most vulnerable pertussis patients that require hospitalization treatment. Our results highlight the urgency of large-scale active surveillance of pertussis in China.