Analysis and comparison of chickenpox outbreaks in two schools at different educational stages: a mixed retrospective...

Varicella (commonly known as chickenpox) poses a major public health challenge in China, frequently triggering public health emergencies within schools. Distinct age demographics and vaccination rates drive divergent epidemic patterns in primary versus high schools, necessitating comparative analysis of outbreak characteristics and interventions to optimize targeted prevention strategies.

A mixed retrospective observational study was conducted to systematically assess varicella outbreaks across two Shenzhen schools, quantifying key epidemiological parameters including outbreak duration and serial intervals. We employed a multidimensional analytical framework to characterize intergenerational transmission patterns and compare epidemic progression between distinct educational stages. Intervention effectiveness was rigorously evaluated through stratified analyses of gender-specific attack rates and vaccine-conferred immunity.

The proportion of cases presenting with a rash as the initial symptom in primary school students (60.41%) was significantly higher compared to high school students (34.78%) (χ² = 9.28, P = 0.002). Fever was found to correlate with a longer recovery period for high school students (P = 0.01), while breakthrough varicella (BV) cases in primary school had a shorter recovery time at School A (10.15 ± 2.83 days) compared to School B (P = 0.003). The duration of illness was longer for primary school cases than for high school cases (15.0 days vs. 9.5 days) in the fourth generation stage. The varicella vaccine offered enhanced protection for primary school students at all stages of outbreak. We observed that the absence of emergency vaccination implementation and class suspension was associated with OR of 3.336 (95%CI:1.272-8.747) and 2.122 (95%CI:1.130-3.985), respectively. Intervention measures exhibited varying effects on disease incidence based on gender in both schools. Moreover, emergency vaccination in School A worked across all vaccination history groups, while School B's closure/disinfection only reduced cases in two-dose history recipients (P < 0.05).

The characteristics of individuals affected by varicella outbreaks varied across different stages of education. Analyzing intergenerational epidemic data can enhance our understanding of the pattern of epidemic transmission. Vaccine history in older children exhibited a relatively limited impact on morbidity rates. Beyond emergency vaccination campaigns, complementary containment strategies should be implemented to mitigate school-based varicella outbreaks.

Not applicable.