Influenza and other respiratory viral infections among schoolchildren in Pittsburgh, Pennsylvania, USA

Background: Information on etiology and age-specific burden of respiratory viral infections among school-aged children and the interaction of these infections with influenza remains limited.

Methods: We conducted a cohort study to determine the etiology of ILI (influenza like illness) among 2,519 K-12 students during the 2012-13 influenza season. We determined, by parent interview, the reasons of students’ absences, and obtained nasal swabs from students with ILI-related absences. Generalized, linear, mixed-effect regressions were performed to determine the associations of outcomes, including ILI and laboratory-confirmed respiratory virus infections with age and other covariates.

Results: Overall, 552 ILI-related absences occurred; swabs were obtained from 464 (84%) of these. One or more respiratory viruses were found in 358 (77%) samples. Influenza was found in 195 (42%) samples. Influenza B accounted for 135 (69%) of laboratory-confirmed influenza infections. Rates of influenza B were significantly higher in grades 1 (10.1% 95% CI 6.8%, 14.4%), 2 (9.7% (95% CI 6.6%,13.6%), 3 (9.6% 95% CI 6.5%, 13.5%), and 4 (10.2% 95% CI 7.0%, 14.2%) than in kindergarteners (3.2% 95% CI 1.5%, 6.0%), The likelihood of having influenza B was also lower among children in half-day kindergarten programs compared to children in full-day kindergarten programs (OR = 0.83; 95% CI 0.59 - 0.93).

Conclusion: Acquisition of influenza and other respiratory pathogens in K-12 schools may be reduced by a truncated school day. Further studies are needed in order to determine if half-day at school instruction would have an effect on controlling influenza and other ILI-related viral respiratory disease outbreaks in school.