Factors Associated with More Severe Disease in Infants and Children with Pertussis in the Post-Pandemic Era: A Single-Center Retrospective Study.

Pertussis remains a potentially severe respiratory illness in pediatric populations, especially in vulnerable groups. A severe outbreak has been reported in the post pandemic era, but it is uncertain if risk factors for severe disease may have changed compared with pre-pandemic years. We conducted a retrospective analysis of children diagnosed with Bordetella pertussis infection at a single tertiary pediatric center, from January 2023 to May 2024 Clinical and demographic variables were compared between outpatients and hospitalized patients to identify factors associated with disease severity. A total of 71 patients were included. Younger age (p < 0.001), lower body weight, (p = 0.0005) and lack of vaccination (p < 0.00001) were significantly associated with hospitalization. No significant differences were found regarding clinical symptoms, oxygen saturation, fever, or viral co-infection. Conclusion: Unvaccinated status, younger age, and lower weight appear to be key risk factors for hospitalization in pediatric pertussis, underlining the protective role of vaccination and the vulnerability of younger infants. These findings support targeted vaccination efforts and early risk stratification to prevent severe disease in vulnerable infants.