Abstract
Background：Vaccination-induced PT-IgG offers protective effects against pertussis, and there is an inverse correlation between antibody levels and disease severity. However, there is limited research exploring the relationship between PT-IgG levels and disease severity in unvaccinated children with acute pertussis.
Method：This study collected data from 302 unvaccinated children with acute pertussis. The aim was to investigate the relationship between disease-induced PT-IgG levels and the severity of pertussis.
Result：302 patients were divided into four groups based on their antibody levels. Most patients (83.77%) had antibody levels below 50.00IU/ml, while a smaller portion (16.23%) had levels above 50.00IU/ml. The length of hospital stay decreased significantly as antibody levels increased (P=0.044). Similar trends were observed for the highest WBC and Lymphocyte count during infection; and these differences were statistically significant (P<0.001 for both). There were no significant differences in the highest heart rate and respiratory rate among the patients (P=0.379 and P=0.963, respectively);Complication, including pneumonia, severe pneumonia, and respiratory failure, also showed no significant differences among the groups (P=0.400, P=0.158, and P=0.131, respectively).Raised C-reactive protein and raised Procalcitonin levels did not differ significantly between the groups (P=0.285 and P=0.170, respectively). Additionally, there were no significant differences in bacterial or viral co-infection rates among the groups (P=0.698 and P=0.623, respectively).
Conclusion：In Chinese infant patients with acute pertussis who have not received vaccination, the PT-IgG levels are predominantly below 50.00IU/ml. Despite the protective role of PT-IgG, higher antibody levels do not appear to significantly reduce the severity.