Researchers investigate the possibility that SARS-CoV-2 can be transmitted by the wind

By Tarun Sai LomteReviewed by Danielle Ellis, B.Sc.Jun 30 2022

In a recent study posted to Research Square*, researchers investigated whether wind-assisted transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was possible.

*Important notice: Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Background

In an American study, 46% of patients with coronavirus disease 2019 (COVID-19) reported known contacts, indicating that infection could spread via less apparent routes. Evidence of the aerosol-mediated transmission of viral infections, including COVID-19, is increasing. Aerosol transmission of SARS-CoV-2 was reported inside a quarantine facility, and an outbreak in a cruise ship reinforces the possibility of aerosol transmission.

Under experimental conditions, the aerosolized SARS-CoV-2 was viable for three hours in 65% relative humidity. Another experimental study reported that the viability of aerosolized virus in artificial saliva was up to five hours. Because SARS-CoV-2 was viable up to the tested duration, the actual period of its viability remains unclear. Therefore, it is possible that viral particles carried by wind could cause an increase in COVID-19 cases downwind.

The study and findings

The present study tested whether COVID-19 infections soar following wind change. COVID-19 hotspots in the United Kingdom (UK) during the initial pandemic phase were identified. Case trends in hotspots were analyzed upwind and downwind within 14 days of wind change.

The wind was southwesterly in West Midlands until mid-March and variable after that. Data from Wolverhampton, Birmingham, Dudley, Walsall, Sandwell, and Coventry were combined into the West Midlands area. The northeasterly wind blew twice during March 26 – 31 and April 17 – 23, 2020. Data from Worcestershire and Warwickshire were combined (henceforth WosWar) for analysis.

COVID-19 cases peaked on April 3, 2020, in West Midlands and WosWar and declined after that, a trend similar to the UK. Case rates plateaued in WosWar from April 7, 12 days post first wind change. The decrease in COVID-19 cases was slower in WosWar than in West Midlands after the second wind change.

In contrast, case trends in Staffordshire (north to and upwind of West Midlands) were distinct. Case rates peaked on April 4 before dropping and increased steadily from April 8, after the first wind change. Next, they investigated a known hotspot, Sheffield, northeast of Staffordshire. A northeasterly wind blew into Staffordshire thrice from March – April 2020.

Cases increased from April 8, 12 days post first wind change and peaked on April 15. Cases rates increased from April 18, after the second wind change. A third wind change began during this surge. In Sheffield, case rates declined from April 30, while case trends remained plateaued until May 5 in Staffordshire. Notably, COVID-19 cases soared sharply after testing for essential workers was mandated on April 23.

Northeasterly winds blew twice between March 26 – 31 and April 18 – 22, traveling across London into Surrey. COVID-19 cases peaked between April 5 and 8 in London and April 6 in Surrey. A steady increase in COVID-19 cases commenced 13 days after the first wind change from April 8, plateauing until April 17. Cases in Surrey and London continued to decline after the second wind change.

A southerly wind blew from London during March 23 – 25 to the north into Buckinghamshire, Essex, and Hertfordshire (BEH). This wind change coincided with the increasing case rate in BEH. Cases peaked in BEH on April 9 before dropping. Another southerly wind blew between April 4 and 7, and the rate of decline was slower 12 days after April 16 and plateaued between April 24 and 29.

A southerly (April 4, 5) and southwesterly (April 7) wind blew into Northumberland from County Durham and Tyne and Wear. COVID-19 cases increased significantly in Northumberland eight days after the wind change, and meanwhile, cases in County Durham and Tyne and Wear were already peaked and began to drop. Eight days after the southerly wind, cases in Northumberland increased while those in County Durham and Tyne and Wear decreased.

Conclusions

The study observed an increase in COVID-19 cases downwind following a wind change, probably due to wind-assisted spread/transmission of SARS-CoV-2 particles from a hotspot to adjacent regions. The authors believed that places beyond those analyzed in this investigation might also have an effect. Overall, the possibility of SARS-CoV-2 transmission by wind has critical implications for preventing its spread, and more research is required to address the aerosol transmission of the virus.

*Important notice: Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.