Airborne transmission of SARS-CoV-2
GS Paper 2 (Diseases)
Airborne transmission of SARS-CoV-2 virus causes more severe lung damage in comparison to infection via fomites—exposure to contaminated surfaces, said new research by National Institutes of Health scientists in the USA. The study, published in Nature Communications, defines how different routes of virus exposure are linked to disease severity.
- Virus transmission via fomites—exposure from contaminated surface contact — is markedly less efficient than airborne transmission but does occur, the study said.
- To investigate how different routes of exposure affected disease development, the scientists exposed hamsters to SARS-CoV-2 via both aerosols and fomites.
- For aerosol exposure, the scientists used equipment that controlled the size of virus-loaded droplets. For fomite exposure, they placed a dish contaminated with SARS-CoV-2 in the animal cages.
- The scientists found that aerosol exposure directly deposited SARS-CoV-2 deep into the lungs, whereas fomite exposure resulted in initial virus replication in the nose.
- Regardless of exposure route, animals had SARS-CoV-2 replicating in the lungs, but lung damage was more severe in aerosol-exposed animals.
- A second part of the study compared animal-to-animal transmission of the virus through the air and in contaminated cage environments (fomites). Airborne droplets are a key SARS-CoV-2 transmission route.
- An additional experiment, using air flowing from infected to uninfected animals, supported the finding that reversing the airflow from uninfected to infected animals greatly reduced transmission efficiency.
- The findings support public health guidance focused on interventions to reduce indoor airborne transmission.
- These efforts include masking, increasing air filtration and social distancing, as well as handwashing and regular surface disinfection, particularly in clinical settings.