Abstract
The airborne transmission of SARS-CoV-2 is still debated. The aim of this rapid review is to evaluate the COVID-19 risk associated with the presence of air-conditioning systems. Original studies (both observational and experimental researches) written in English and with no limit on time, on the airborne transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 coronaviruses that were associated with outbreaks, were included. Searches were made on PubMed/MEDLINE, PubMed Central (PMC), Google Scholar databases, and medRxiv. A snowball strategy was adopted to extend the search. Fourteen studies reporting outbreaks of coronavirus infection associated with the air-conditioning systems were included. All studies were carried out in the Far East. In six out the seven studies on SARS, the role of Heating, Ventilation, and Air Conditioning (HVAC) in the outbreak was indirectly proven by the spatial and temporal pattern of cases, or by airflow-dynamics models. In one report on MERS, the contamination of HVAC by viral particles was demonstrated. In four out of the six studies on SARS-CoV-2, the diffusion of viral particles through HVAC was suspected or supported by computer simulation. In conclusion, there is sufficient evidence of the airborne transmission of coronaviruses in previous Asian outbreaks, and this has been taken into account in the guidelines released by organizations and international agencies for controlling the spread of SARS-CoV-2 in indoor environments. However, the technological differences in HVAC systems prevent the generalization of the results on a worldwide basis. The few COVID-19 investigations available do not provide sufficient evidence that the SARS-CoV-2 virus can be transmitted by HVAC systems.
Highlights
Many countries have responded to the “Coronavirus disease 2019” (COVID-19) pandemic caused by the emerging infectious agent termed as “Severe Acute Respiratory Coronavirus type 2” (SARS-CoV-2)by adopting stringent containment measures, such as the so-called lockdown
We utilized the participants–exposure–comparisons–outcome (PECOS) criteria, and we defined them according to evidence-based practice [32]—P is human subjects residing in indoor environments, E is exposed to air-conditioning systems (HVAC), C is any comparison between the pathogens under study, and O is respiratory infection outbreaks caused by Severe Acute Respiratory Syndrome (SARS)-CoV-1, MERS-CoV, or SARS CoV-2
We found 14 studies reporting outbreaks of coronavirus infection in indoor environments (Table 1)
Summary
Many countries have responded to the “Coronavirus disease 2019” (COVID-19) pandemic caused by the emerging infectious agent termed as “Severe Acute Respiratory Coronavirus type 2” (SARS-CoV-2)by adopting stringent containment measures, such as the so-called lockdown. Public Health 2020, 17, 6052; doi:10.3390/ijerph17176052 www.mdpi.com/journal/ijerph
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