Respiratory viral coinfection in a birth cohort of infants in rural Nepal.

BACKGROUND Acute respiratory illnesses are a leading cause of global morbidity and mortality in children. Coinfection with multiple respiratory viruses is common. Although the effects of each virus have been studied individually, the impacts of coinfection on disease severity are less understood. METHODS A secondary analysis was performed of a maternal influenza vaccine trial conducted between 2011 and 2014 in Nepal. Prospective weekly household-based active surveillance of infants was conducted from birth to 180 days of age. Mid-nasal swabs were collected and tested for respiratory syncytial virus (RSV), rhinovirus, influenza, human metapneumovirus (HMPV), coronavirus, parainfluenza (HPIV), and bocavirus by RT-PCR. Coinfection was defined as the presence of two or more respiratory viruses detected as part of the same illness episode. RESULTS Of 1730 infants with a respiratory illness, 327 (19%) had at least two respiratory viruses detected in their primary illness episode. Of 113 infants with influenza, 23 (20%) had coinfection. Of 214 infants with RSV, 87 (41%) had coinfection. The cohort of infants with coinfection had increased occurrence of fever lasting ≥ 4 days (OR 1.4, 95% CI: 1.1, 2.0), and so did the subset of coinfected infants with influenza (OR 5.8, 95% CI: 1.8, 18.7). Coinfection was not associated with seeking further care (OR 1.1, 95% CI: 0.8, 1.5) or pneumonia (OR 1.2, 95% CI: 0.96, 1.6). CONCLUSION A high proportion of infants had multiple viruses detected. Coinfection was associated with greater odds of fever lasting for four or more days, but not with increased illness severity by other measures.