Retrospective study links vaccination status, co-infection and white blood cell count to poor prognosis in severe pediatric pertussis

A retrospective observational study of 80 children hospitalized with severe pertussis in Shandong Province, China, from January 2022 through December 2024, found exploratory associations between poor in-hospital prognosis and unvaccinated status, mixed bacterial-viral co-infection and higher white blood cell count. The study abstract reports that multivariable logistic regression identified all three factors as independent correlates of a composite endpoint comprising new invasive mechanical ventilation, pertussis encephalopathy with persistent neurological sequelae, or all-cause in-hospital death. Six of the 80 children, or 7.5%, met this composite endpoint.

The cohort was restricted to children already diagnosed with severe pertussis, so the analysis did not identify factors predicting progression from mild to severe disease. The median age was 4 months and 19 days, with a range of 1 month and 14 days to 5 years. Of the participants, 52 (65.0%) were no more than 3 months old and had not reached routine diphtheria, pertussis and tetanus vaccination age. All children presented with paroxysmal cough, and 95% had an inspiratory whoop. Leukocytosis, defined as a white blood cell count above 20 × 10⁹/L, was observed in 45.0% of the cohort; patent foramen ovale was reported in 75.0%, and secondary cardiac abnormalities developed in 18.80%.

After adjustment for age-related vaccination eligibility, the regression analysis found associations between the composite poor-prognosis endpoint and unvaccinated status (odds ratio, 4.2; 95% confidence interval, 1.8–9.6; P = 0.001), mixed bacterial-viral co-infection (odds ratio, 3.5; 95% CI, 1.2–10.1; P = 0.023), and elevated continuous white blood cell count (odds ratio, 5.1; 95% CI, 2.3–11.4; P < 0.001). White blood cell count was retained as a continuous variable rather than categorized in the regression model. Receiver operating characteristic analysis also derived a descriptive cutoff above 30 × 10⁹/L, but this threshold was not used for modelling and was presented only as a possible bedside reference.

Prognostic discrimination was modest. The continuous white blood cell count alone yielded an area under the ROC curve of 0.678, while the combined model produced an AUC of 0.689. Children receiving erythromycin combination therapy had a higher observed frequency of liver dysfunction than those receiving monotherapy, 36.40% versus 8.60% (P < 0.05), but the abstract does not establish that combination therapy caused the difference or assess its effect on prognosis. The main limitation was the small number of poor-prognosis events—six among 80 participants—which limits the precision and generalisability of the adjusted estimates. The authors characterized the findings as exploratory and said the indicators require external validation before clinical application.

Subject of Research: Clinical indicators associated with poor in-hospital prognosis in children hospitalized with severe pertussis

Article Title: Clinical characteristics and indicators associated with poor in-hospital prognosis among children with severe pertussis in Shandong Province, China (2022–2024)

Article References: Wang, P., & Li, J. (2026). Clinical characteristics and indicators associated with poor in-hospital prognosis among children with severe pertussis in Shandong Province, China (2022–2024). BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14438-5

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14438-5

Keywords: severe pertussis, pediatric infectious disease, in-hospital prognosis, white blood cell count, bacterial-viral co-infection, vaccination status, retrospective cohort, Shandong Province, ROC analysis, multivariable regression, Clinical, characteristics