Aerosol and Surface Transmission Potential of SARS-CoV-2
Aerosol and Surface Transmission Potential of SARS-CoV-2. . Jefferson T, Heneghan C.
Published on July 27, 2020
Transmission Dynamics of COVID-19
||Santarpia JL, Rivera DN, Herrera V et al. Aerosol and Surface Transmission Potential of SARS-CoV-2. medRxiv. 2020:2020.03.23.20039446.
||University of Nebraska Medical Center
||Droplet, Person to person, Close contact, Fomite,
All samples taken were COVID 19 cases in isolation facilities were contaminated, indicating that SARS-CoV-2 may spread through both direct (droplet and person-to-person) as well as indirect mechanisms (contaminated objects and airborne transmission). The concentration of contamination was independent of patients’ symptoms and coughing. The findings support the use of airborne isolation precautions when caring for COVID-19 patients.
The study found that 71% of all personal items sampled were positive for SARS-CoV-2 (cellular phones were 78% positive, remote controls for in-room televisions were 56% positive, samples of toilets were 81% positive, 71% of the bedside tables and bed rails and 73% of the window ledges, all the floor beneath patients’ beds’ samples and four-fifths of ventilation grates tested positive by RT-PCR. Samples taken in the hallways were 58.3% positive.
The highest airborne concentrations were recorded by personal samplers in the Nebraska Biocontainment Unit while the patient was receiving oxygen through a nasal cannula. No cough was observed while sampling was taking place. Correlation between the strength of positivity of samples and symptoms was weak. An air sample and a window sill sample had weak replication results.
What did they do?
The study reports the results of environmental sampling (air and surface) around thirteen individuals in isolation for Covid-19 on days 5 to 9 and 10 of occupancy. Additional samples were obtained on day 18 after another patient had been admitted to the unit for four days. The surface samples came from common room surfaces, personal items, and toilets.
The patients are not described nor are the histories, There are no accurate plans of the isolation facilities. A small study that requires replication.
|Clearly defined setting
||Demographic characteristics described
||Follow-up length was sufficient
||Transmission outcomes assessed
||Main biases are taken into consideration
What else should I consider?
About the authors
Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings
Tom Jefferson, epidemiologist.