Vaccine. 2025 Apr 2;53:127081. doi: 10.1016/j.vaccine.2025.127081. Online ahead of print.
ABSTRACT
BACKGROUND: In 2024, the reported incidence of pertussis in China has increased sharply. As a vulnerable group, neonates continue to be at highest risk of severe outcomes from pertussis infection. However, there have been no serological assessment of population immunity since the 2024 pertussis outbreak in China. This study aimed to ascertain the PT-antibody status of pregnant women and their newborns during the epidemic period and offer insights to maternal immunization in China.
METHODS: From April to June 2024, 227 newborn-mother pairs in Xiamen City were recruited to test serum anti-PT IgG levels by ELISA. The geometric mean, undetectable rate (< 5 IU/mL), seropositivity rate (≥ 40 IU/mL), recent infection rate (≥ 100 IU/mL), and newborn-to-maternal ratio of anti-PT IgG were calculated. Statistical analysis was made based on maternal age, gravidity, parity, delivery mode, gestational age and newborn sex.
RESULTS: The anti-PT IgG levels were positively correlated (R2 = 0.761) between pregnant women and their newborns. We found that 97.8 % of participants were seronegative, and 75.3 % of pregnant woman and 64.3 % of newborn had anti-PT IgG levels below 5 IU/mL. The seropositive prevalence of them were both only 2.2 % (95 % CI 0.9-5.1). The newborn-to-maternal ratio was stable in the range of 1.1 to 1.3 across all groups. There was no significant difference in the anti-PT IgG level of all participants across maternal and neonatal demographic characteristics. There was also no significant difference in the prevalence of seropositivity across demographic characteristics, except for delivery mode among newborns.
CONCLUSIONS: Almost all of the pregnant women and their newborns in this study had anti-PT IgG levels low enough to suggest susceptibility to pertussis infection, especially during an epidemic period. Infants are unprotected until the onset of primary immunization series, which would support the rationale for maternal immunization.
PMID:40179439 | DOI:10.1016/j.vaccine.2025.127081