Is it Covid-19 Airborne?

One of the hottest topics at Covid-19 is the potential and scale of airborne transmission. Since the onset of the pandemic World Health Organization maintains low likelihood of airborne transmission And that The transmission of the virus is primarily due to contaminated surfaces and the large droplets caused by speech, coughing and sneezing...

Based on contact and penetration of large droplets, preventative measures such as disinfecting surfaces, washing hands, wearing a mask, and keeping at least 6 feet away from others are very effective. However, there are some Report of infection Where no physical or droplet contact has been reported Evidence of airborne infections continues to grow..

What is airborne transmission?

The main difference between airborne and droplet penetration is that large droplets fall to the ground within about 6 feet. The generality of this rule is DisputedThe agreed exception is that very small droplets (called aerosols) with a diameter of 5 micrometers or less can stay in the air for long periods of time. Aerosolized particles not only stay for long periods of time, they can also continue air flow, And therefore move farther than the droplet. When Covid-19 virus particles are aerosolized, they are stable and up to 16 hours..

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What is the evidence for Covid-19’s airborne spread?

It has proven difficult to determine how many Covid-19 clusters or individual cases should be attributed to aerosols. The main reason lies in the difficulty of culturing SARS-CoV-2, the virus that causes Covid-19, collected from the air. Delicate virus envelope Damaged during the process of aerosol collection, The recovery rate of virus particles in culture is low. An alternative to virus collection and culture is to sample RNA. The problem with that is that Covid-19 RNA may be present in the sample but it does not prove the presence of live virus. Basically, this is a measurement issue.

It was difficult to find direct evidence of airborne transmission, but many studies have found much indirect evidence. 1 analysis Data from 14 hospitals that collected air samples from Covid-19 patient rooms were summarized. Of these hospitals, half of the air samples collected were positive for Covid-19, and two had collection points more than 6 feet away from the patient, suggesting particle escape from the 6 foot zone. I will. This means that they are lighter aerosols, not larger droplets.

another Investigation Six to 15 feet of viable virus were isolated from two positive patients. Some medical procedures such as Ventilation or intubation These patients were not subject to these procedures when artificially producing aerosols. This suggests that infectious aerosols may be naturally produced by Covid-19 patients.

There is also evidence from case studies. As an example, Diner infected in a restaurant.. Ten individuals were sitting between three adjacent tables. Researchers reviewed the video footage of the restaurant to make sure it did not make direct contact between the tables or share potentially contaminated objects (known in medical terms as “fomites”). confirmed. The tables were 15 feet apart. Subsequent measurements of airflow in the restaurant combined with computer simulations show that the pattern of infection distribution is most consistent with the aerosol produced by normal exhalation.

Another outbreak that causes airborne infections is Sightseeing bus.. Eight out of 49 people on the bus were infected with one index patient. The most interesting thing about the epidemic is that one of the infected people sat 15 feet from the index case and came in and out of another door, virtually eliminating the possibility of extended contact.

The bottom line is that there is still no direct evidence that Covid-19 is airborne, but the indirect case is overwhelming. More difficult is to quantify the number of cases caused by aerosolized virus particles and the most effective interventions to stop the spread.

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