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Can COVID-19 be transmitted through the air?

Medically reviewed by Drugs.com Last updated on Apr 7, 2020.

Official Answer

by Drugs.com

Yes, the new coronavirus SARS-CoV-2 can be transmitted through the air, but whether or not it is airborne is still a matter that experts are debating.

Transmitted through the air vs airborne - what’s the difference?

SARS-Cov-2 is thought to be primarily spread between people via infected respiratory droplets that are released when an infected person coughs, sneezes or exhales. These droplets are most likely to infect people in close proximity (within 6 feet) via a process called droplet transmission.

Given that the infected respiratory droplets are moving through the air before infecting someone else, many people might be wondering why we’ve been told the virus isn’t airborne. Scientists, however, consider airborne transmission to be different from droplet transmission and this all comes down to the size of the droplets being spread.

Droplets greater than 5-10 m in diameter are considered to be respiratory droplets and even though they can spread through the air they are not considered to be ‘airborne’. Droplets (or aerosols) smaller than 5 um in diameter, called droplet nuclei, can remain in the air for longer periods of time and travel further distances. This type of droplet is said to be airborne.

Is it possible that SARS-CoV-2 is actually airborne?

On March 27, 2020, the World Health Organization (WHO) indicated that in certain circumstances airborne transmission of SARS-CoV-2, the new coronavirus that causes COVID-19, is possible. This might occur when, for example, a patient is being intubated or using a nebulizer because aerosols containing the virus could be generated during these procedures.

Scientists have also been investigating the possibility that SARS-CoV-2 could be airborne, but the research is still limited and some research does not show that the virus is airborne. The evidence, however, seems to be growing in favor of the possibility that it may be.

On April 1, 2020, the US National Academy of Sciences (NAS) sent the White House a letter, which acknowledged that limited research had been conducted, but which also stated that “the results of available studies are consistent with aerosolization of virus from normal breathing”.

The letter from the NAS highlights the results of a study conducted at the University of Nebraska Medical Center, which suggested that viral aerosol particles are produced by patients with COVID-19, even when they do not cough. Further experiments are ongoing to determine the viral activity of the viral aerosol particles produced by such patients. Low concentrations of virus were recovered from the samples obtained during the study, making it difficult to determine if virus in the particles was capable or likely to cause infection in another person.

Help stop the spread of COVID-19

Preliminary evidence suggests SARS-CoV-2, may be airborne, although further research is necessary to fully understand how the virus spreads. In the meantime, to help stop the spread of COVID-19, make sure that when you’re indoors the areas you are in are well ventilated. Opening windows or doors can help improve ventilation. And, if you’re out in public then follow the US Centers for Disease Control and Prevention’s (CDC) advice and wear a facemask.

References
  • World Health Organization (WHO). Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations. March 27, 2020. [Accessed April 7, 2020]. Available online at: https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations.
  • The National Academy of Sciences. Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS-CoV-2 for the COVID-19 Pandemic. April 1, 2020. [Accessed April 7, 2020]. Available online at: https://www.nap.edu/read/25769/chapter/1.
  • Ong SWX, Tan YK, Chia PY, et al. Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a Symptomatic Patient. JAMA. Published online March 4, 2020. doi:10.1001/jama.2020.3227.
  • Santarpia JL, Rivera DN, Herrera V, et al. Transmission Potential of SARS-CoV-2 in Viral Shedding Observed at the University of Nebraska Medical Center. medRxiv [Accessed April 7, 2020]. doi: https://doi.org/10.1101/2020.03.23.20039446.
  • Centers for Disease Control and Prevention (CDC). Coronavirus Disease 2019 (COVID-19). How to Protect Yourself & Others. [Accessed April 7, 2020]. Available online at: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

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