nasal carriage patterns with and without common respiratory virus detections in households in Seattle, WA, USA before and during the COVID-19 pandemic.

BACKGROUND

Respiratory viruses might influence nasal carriage and subsequent disease risk. We estimated the association between common respiratory viruses and semiquantitative nasal carriage density in a household setting before and during the COVID-19 pandemic.

METHODS

From November 2019-June 2021, we enrolled participants in a remote household surveillance study of respiratory pathogens. Participants submitted weekly reports of acute respiratory illness (ARI) symptoms. Mid-turbinate or anterior nasal swabs were self-collected at enrollment, when ARI occurred, and, in the second year of the study only, from household contacts after SARS-CoV-2 was detected in a household member. Specimens were tested using multiplex reverse-transcription PCR for respiratory pathogens, including , rhinovirus, adenovirus, common human coronavirus, influenza A/B virus, respiratory syncytial virus (RSV) A/B, human metapneumovirus, enterovirus, and human parainfluenza virus. We estimated differences in semiquantitative nasal carriage density, estimated by the inverse of relative cycle threshold (Crt) values, with and without viral detection for any virus and for specific respiratory viruses using linear generalized estimating equations of Crt values on virus detection adjusted for age and swab type and accounting for clustering of swabs within households.

RESULTS

We collected 346 swabs from 239 individuals in 151 households that tested positive for ( = 157 with and 189 without ≥1 viruses co-detected). Difficulty breathing, cough, and runny nose were more commonly reported among individuals with specimens with viral co-detection compared to without (15%, 80% and 93% vs. 8%, 57%, and 51%, respectively) and ear pain and headache were less commonly reported (3% and 26% vs. 16% and 41%, respectively). For specific viruses among all ages, semiquantitative nasal carriage density was greater with viral co-detection for enterovirus, RSV A/B, adenovirus, rhinovirus, and common human coronavirus ( < 0.01 for each). When stratified by age, semiquantitative nasal carriage density was significantly greater with viral co-detection among children aged <5 ( = 0.002) and 5-17 years ( = 0.005), but not among adults aged 18-64 years ( = 0.29).

CONCLUSION

Detection of common respiratory viruses was associated with greater concurrent semiquantitative nasal carriage density in a household setting among children, but not adults.