TraVerse: A method of natural respiratory virus transmission from symptomatic children to healthy young adults

A method of natural transmission that ‘traverses’ all identified common cold viruses was evaluated in Leicester, UK during 2012 to 2015. The viruses were: adenovirus, coronavirus, enterovirus, influenza, metapneumovirus, parainfluenza, rhinovirus, and RSV. Mechanisms of transmission assessed included large droplet, hand contact, fomite, and aerosol. Aim: to augment current understanding of natural respiratory virus transmission using the TraVerse method. Methods: TraVerse method of 30-minute interactions between symptomatic paediatric inpatients and healthy young adults in a fully functioning hospital ward. Swab and aerosol samples were tested using qualitative and quantitative PCR. Illness severities were evaluated using daily symptom diary cards. Results: The overall RT-PCR positivity rates were 93% for children and 22% for adults. Rates of natural transmission, depending on the virus, were 4% - 24% by large droplet, 18% - 19% by hand contact, 50% - 100% by self-inoculation, and 8% - 33% by fomites. Aerosol transmission was not established. Adults did not shed flu, coronavirus, metapneumovirus, or parainfluenza; nevertheless, severe illness occurred in 26% whose child pairs had mono-infections of these viruses. When ill, only 7% of adults stayed home, and only 4% sought medical attention. Asymptomatic rhinovirus transmission occurred at a rate of 5%. Conclusions: TraVerse was fit-for-purpose in elucidating natural, human-to-human respiratory virus transmission rates. Aerosol transmission may be the primary mechanism in the natural transmission of flu, coronavirus, metapneumovirus, and parainfluenza but was not appropriately evaluated because of funding constraints. Paediatric mouthing has relevance in nosocomial transmission. Healthy adults develop severe illness but do not generally stay home, take medications, or seek medical advice. Recommendations: Sanitizing of paediatric patients’ hands, use of masks to discourage face-touching, flocked swabs to replace nasopharyngeal aspirates in respiratory sampling, use of virus molecular subtyping assays, increased efforts to include minorities in research, and better collaboration to encourage research funding.