# Pertussis epidemiology and seroprevalence in Wujin District, Changzhou, China, 2024

## TL;DR

In 2024, Wujin District in China saw a major whooping cough outbreak, with low immunity in many people, especially adolescents and adults.

## Contribution

This study provides new insights into pertussis epidemiology and immunity levels in Wujin District, highlighting the need for targeted surveillance.

## Key findings

- The 5–9 year age group had the highest proportion of pertussis cases in Wujin District in 2024.
- Over 49% of participants had undetectable pertussis antibodies, with the lowest positivity in the 20–29 years age group.
- Vaccinated individuals showed higher antibody levels than unvaccinated or those with unknown vaccination status.

## Abstract

China experienced its worst pertussis epidemic in 30 years during 2024, and Wujin District faced the same challenge. This study aims to investigate the epidemiological characteristics of pertussis and the immune status of the healthy population in Wujin District, Changzhou City.

The study employed descriptive epidemiology for pertussis case analysis and a serological survey for population antibody assessment in Wujin District, 2024. The level of pertussis toxin (PT) IgG antibody was measured by the Enzyme-Linked Immunosorbent Assay (ELISA).

A total of 28 pertussis cases were reported in 2024 in Wujin District, with an incidence rate of 2.15 per 100,000 population. Although infants < 1 year had the peak incidence (84.02 per 100,000), the 5–9 year age group accounted for the largest proportion of cases (67.86%) with an incidence rate of 28.70 per 100,000. 521 participants were included in the serological survey. Anti-PT IgG levels were undetectable (< 5 IU/ml) in 49.52% of the participants. The overall positivity (≥ 20 IU/mL) rate and antibody concentration were 17.27% and 5.17 IU/mL, respectively. The antibody positive rate was highest in the 1.5–3 years age group (30.00%) and lowest in the 20–29 years age group (7.89%). The recent infection (≥ 80 IU/mL) rate was 2.11%, with the top two observed in the 6–9 years old group (7.69%) and the 10–14 years old group (5.88%). The seropositivity rates and antibody concentrations of vaccinated individuals were higher than those of unvaccinated subjects or those with unknown vaccination history (all P-values < 0.05).

Wujin District saw a striking predominance of pertussis cases in school-aged children (5–9 years) in 2024. The antibody levels against pertussis in the healthy population were generally low, especially among adolescents and adults, calling for reinforced active surveillance targeting these age groups.

Not applicable.

The online version contains supplementary material available at 10.1186/s12879-026-12799-5.