ASTHMA EXACERBATIONS are frequently triggered by common cold infections. Whereas prior studies have swabbed individual patients to detect viruses, we take a population level approach to investigate common cold circulation and its consequences for asthmatics. We introduce a dynamic model of common cold transmission with different contact patterns for adults and children, which are modified by school vacations. By jointly fitting this and an asthma risk model to daily hospitalization rates in eight large cities in Texas, we found that the common cold is a primary driver of asthma exacerbations, and both are predictably influenced by the school calendar. SOURCE: PNAS.

EDITOR’S QUOTE: “For children, we find that daily viral prevalence is the strongest predictor of asthma hospitalizations, with transmission reduced by 45% (95% credible interval =41–49%) during school closures. We detect a transient period of nonspecific immunity between infections lasting 19 (17–21) days.”