Respiratory Viral Coinfection in a Birth Cohort of Infants in Rural Nepal

Acute respiratory illnesses are a leading cause of global morbidity and mortality in children. Although the effects of each virus have been studied individually, impacts of coinfection on disease severity are less understood. A secondary analysis was performed of a maternal influenza vaccine trial conducted between 2011-2014 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 various viral pathogens by RT-PCR. Of 1,730 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. Infants with coinfection had increased occurrence of fever lasting 4 days overall (OR 1.4, 95% CI: 1.1, 2.0), and in the subset of 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). A high proportion of infants experiencing their first respiratory illness had multiple viruses detected. Coinfection was associated with longer duration of fever, but not with increased illness severity by other measures.