Tuberculosis can be transmitted through airborne dust particles. Until recently, the World Health Organization (WHO) believed, based on scientific research, that the only way to contract coronavirus was through contact with a surface on which the virus had landed. This is because the coronavirus spreads through droplets released during coughing and sneezing. As a result, the WHO has identified handwashing as the main preventive measure against infection. But now the organization has reported that in some cases, the possibility of airborne transmission of infection cannot be ruled out. This means that the virus can spread in tiny particles that are released when a person talks or breathes. If confirmed, recommendations to stay indoors may be reconsidered.
Airborne transmission occurs when we breathe in viruses or bacteria on dust particles that can remain in the air for several hours. These much smaller droplets can spread further. Airborne infections such as tuberculosis, influenza, and pneumonia are spread through the air. WHO acknowledges that there is evidence that coronavirus transmission may occur in enclosed spaces and large gatherings of people. The research found that artificially dispersed coronavirus can remain in the air for at least three hours. But scientists note that the experiments were conducted in a laboratory, where conditions are different from everyday life, and the results may vary. Cases of so-called “super-spreading” of the coronavirus have further strengthened the notion of possible airborne transmission. In the US town of Mount Vernon, one person infected at least 45 choir members during a rehearsal.
If it is confirmed that the virus can be transmitted by airborne particles, the recommendations may be revised. Many of those who were infected at that time did not violate the rules of social distancing. A similar case occurred in the Chinese city of Guangzhou – the carrier of the virus reportedly infected nine restaurant patrons at once. According to scientists, one of the infected people was six meters away from the virus carrier. Control measures depend on how the virus is spread. The WHO currently recommends washing hands with warm water and soap for 20 seconds and social distancing.
Social distancing indoors may not be sufficient. But now some scientists argue that these measures – while very important – are not enough to combat the virus, which is transmitted through airborne particles. So far, WHO has not added to its recommendations, but the organization is reviewing new data. In the near future, the WHO will probably recommend more frequent use of face masks and strict social distancing, especially in bars, restaurants and public transportation. There may also be stricter rules for premises with air conditioning. 239 scientists from 32 countries wrote an open letter to the WHO this week. They urged the organization to change its recommendations in light of data on airborne transmission of the virus. “We wanted them to acknowledge this information,” said Jose Jimenez of the University of Colorado, one of those who signed the petition. “This is definitely not an attack on WHO. It is a scientific discussion, but we felt it necessary to speak openly because the organization did not want to hear about new data,” he said.
Some scientists are concerned that air conditioners may help the virus spread. Benedetta Allegranzi, coordinator of WHO’s Global Infection Prevention and Control Group, said in response to a message from the scientists that the emerging information on airborne transmission of infection in situations described in crowded and poorly ventilated indoor spaces cannot be dismissed. But the WHO also made clear that more evidence of airborne transmission of the infection is needed before any decisions can be made. WHO advisor David Heymann said the organization needs convincing results from a larger study before developing a new strategy to combat the virus.