SickMix: Temporal Changes in Social Contact Patterns among People with Acute Infection and Their Close Contacts

A study followed 1,000 patients with acute gastroenteritis or acute respiratory infection and 709 household members in the northwestern United States from 2024 to 2025. Results showed that during peak illness, the number of social contacts was substantially reduced, with an average 2.0-fold increase during the two-week follow-up period. Mathematical modeling of disease transmission demonstrated that models accounting for temporary reduction in social contacts during acute infection produced substantially different results compared to models that did not account for this reduction. Human behavior during acute infection significantly impacts disease transmission dynamics and the effectiveness of preventive measures. The study provides an empirical framework for incorporating behavioral changes during illness into infectious disease models.