We conducted prospective, community-wide surveillance for acute respiratory illnesses (ARIs) in Rochester, NY and Marshfield, WI during a 3-month period in winter 2011. We estimated the incidence of ARIs in each community, tested for viruses, and determined the proportion of ARIs associated with healthcare visits. We used a rolling cross-sectional design to sample participants, conducted telephone interviews to assess ARI symptoms (defined as a current illness with feverishness or cough within the past 7 days), collected nasal/throat swabs to identify viruses, and extracted healthcare utilization from outpatient/inpatient records. Of 6492 individuals, 321 reported an ARI within 7 days (4·9% total, 5·7% in Rochester, 4·4% in Marshfield); swabs were collected from 208 subjects. The cumulative ARI incidence for the entire 3-month period was 52% in Rochester [95% confidence interval (CI) 42–63] and 35% in Marshfield (95% CI 28–42). A specific virus was identified in 39% of specimens: human coronavirus (13% of samples), rhinovirus (12%), RSV (7%), influenza virus (4%), human metapneumovirus (4%), and adenovirus (1%). Only 39/200 (20%) had a healthcare visit (2/9 individuals with influenza). ARI incidence was ~5% per week during winter.

The aim of this study was to describe the incidence and risk factors for respiratory morbidity during the 12-month period following the first respiratory syncytial virus (RSV) season in 242 preterm infants [<33 weeks gestational age (GA)] without bronchopulmonary dysplasia and 201 full-term infants (39–41 weeks GA) from the French CASTOR study cohort. Preterm infants had increased respiratory morbidity during the follow-up period compared to full-terms; they were more likely to have wheezing (21% vs. 11%, P = 0·007) and recurrent wheezing episodes (4% vs. 1%, P = 0·049). The 17 infants (14 preterms, three full-terms) who had been hospitalized for RSV-confirmed bronchiolitis during their first RSV season had significantly more wheezing episodes during the follow-up period than subjects who had not been hospitalized for RSV-confirmed bronchiolitis (odds ratio 4·72, 95% confidence interval 1·71–13·08, P = 0·003). Male gender, birth weight <3330 g and hospitalization for RSV bronchiolitis during the infant's first RSV season were independent risk factors for the development of wheezing episodes during the subsequent 12-month follow-up period.