Researchers from the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH) have shown how different routes of virus exposure are linked to disease severity in a study conducted on Syrian hamsters.

For the study, hamsters were exposed to SARS-CoV-2 via both aerosols and fomites. Exposure to aerosols, via equipment that controlled the size of virus-loaded droplets, led to the direct deposition of the virus deep into the lungs, whereas fomite exposure, through a dish contaminated with the virus place in the animal cages, resulted in initial virus replication in the nose. The SARS-CoV-2 was found to be replicating in the lungs regardless of the route of exposure, however, the lung damage was more severe in aerosol-exposed animals compared to the fomite group.

Animal-to-animal transmission of the virus through the air and in contaminated cage environments (fomites) was also investigated, which showed that airborne route transmitted the virus more efficiently than the fomites, suggesting that airborne droplets are a key SARS-CoV-2 transmission route though fomite transmission does occur. Airborne transmission was dependent on the direction of the airflow as reversing the airflow from uninfected to infected animals greatly reduced transmission efficiency.

The study, published in Nature Communications, has shown that besides the exposure dose and the underlying host conditions, exposure route also influences disease manifestation. And, these findings give further credence to the precautionary measures recommended to reduce indoor airborne transmission such as masking, increasing ventilation, social distancing, handwashing and regular surface disinfection.

(Source: NIH News Release, August 17, 2021)