Experts say the evidence of COVID-19 aerial transmission is “overwhelming”

A new review published in Lancet We have presented 10 important scientific reasons why SARS-CoV-2, the virus that causes COVID-19, spreads primarily in the air. The study found that evidence of airborne transmission was “overwhelming,” and the sooner the global health authorities acknowledged it, the sooner more effective measures could be taken to better protect the public. Add to the increase in expert chorus to say.

Perhaps one of the most lively debates in the last 12 months has been exactly how most people catch COVID-19. As the pandemic spread around the world in early 2020, the general view from most public health experts was that SARS-CoV-2 was spread primarily by droplet infection.

This belief relied on traditional binaries between droplets and the transmission of aerosol viruses. Aerosol particles are classically defined as less than 5 micrometers (µm). They remain suspended in the air for extended periods of time and can travel a considerable distance from their source.

Respiratory droplets, on the other hand, are larger particles and are often propelled from their source by coughing or sneezing. These particles fall to the ground in seconds and typically do not move more than 6 feet (1.8 m) from their source.

General estimates from early last year are that SARS-CoV-2 spreads primarily through respiratory droplets, so public health recommends basic measures such as social distance, hand washing, and frequent surface washing. It led to advice. However, as 2020 progresses, more and more case studies present scenarios in which a large number of people are infected with superspreading events, despite being far from the source of the virus.

New review published in LancetHeaded by Trish Greenhalgh of Oxford University, he claims that there is consistent and strong evidence suggesting that SARS-CoV-2 is transmitted primarily via the aerial route. Researchers have provided 10 pieces of evidence over the past year that overwhelmingly support this hypothesis. The review also argues that this new viral respiratory droplet infection is based on a defective and outdated model of viral infection.

This assessment includes a number of case studies documenting long-distance transmission of the virus between people in adjacent hotel rooms and superspreading events in indoor venues that cannot be explained by droplet transmission. Refers to a large amount of evidence of the month. Researchers have known that as many as 100 µm particles remain suspended in the air for extended periods of time, and the old fixed definition of aerosol particles smaller than 5 µm is misleading about how SARS-CoV-2 diffuses. Claims.

“For decades historically, there was a false assumption that proximity-mediated infection meant large flügge droplets and parameters to deny the aerial transmission of tuberculosis and measles,” the researchers said. Are writing in the study. “This has become a medical doctrine, ignoring direct measurements of aerosols and droplets, the overwhelming number of aerosols produced by respiratory activity, and any boundary of particle size between aerosols and droplets (correct boundary of 100 μm). Deficiencies such as) were revealed. “

Researchers are not only seeking widespread approval for aerial SARS-CoV-2 infection. Editor of a prestigious science journal in early February Nature He criticized the Public Health Organization and the World Health Organization for failing to effectively convey the superiority of airborne transmission.

editorial Recognizing the growing acceptance of COVID-19 spreading in the air, continued recommendations for surface disinfection and other droplet propagation prevention measures confuse the general public and shift resources from measures such as improved ventilation. Suggested that it would lead to a huge investment in expensive disinfection efforts. Indoor space.

“This lack of clarity about parameter risk has serious implications compared to the much greater risk posed by airborne propagation.” The journal editor wrote:.. “People and organizations will continue to prioritize costly disinfection efforts if they can emphasize the importance of masks and invest more resources in investigating measures to improve ventilation. Is more complicated, but can make a bigger difference. “

The Centers for Disease Control and Prevention (CDC) in the United States is a good example. The CDC still suggests that COVID-19 spreads primarily through respiratory droplets. Its current advice Although direct contact claims to be the most common vector of infection, the information was recently updated to state that “COVID-19 can be spread by airborne infections.”

A Recent case studies Published by the CDC described the COVID-19 cluster last year at an Australian church. The study reports that 12 people were infected during a two-day church service. Patients in the major cases are members of the Church Choir, and all epidemiological evidence shows aerial spread as the best explanation. Nonetheless, the study also states that “this study only provides circumstantial evidence of airborne transmission.”

New co-author Lancet Zeynep Tufekci, a writer and sociologist at the University of North Carolina at Chapel Hill, states that many of the current precautions based on the droplet propagation hypothesis are still valid. For example, distance and masks are important tools to prevent infection, but she argues that some important public health policies are to divert resources from implementing more useful measures.

“Even after a year, there is widespread use of unnecessary levels of cleaning that undermine public health, the use of plexiglass indoors is not well protected, and instead of paying attention to airflow. It can also be contraindicated, at risk of ventilation and aerosols, “says Tufekci. “To make people feel empowered to make decisions to better protect themselves in different situations, and without adjusting the guidelines globally to meet the best evidence available. , This situation cannot be corrected. “

A recent editorial published in BMJ It argues that the traditional scientific definition of viral infection requires urgent correction. Co-authored by virus aerial transmission expert Linsey Marr, this article states that many of today’s infection control measures are useful and should not be changed even with broad consensus on the aerial transmission advantages. I agree with.

However, the major problem with splash propagation that we are currently focusing on is the lack of emphasis on indoor ventilation. Marr et al. Suggest that immediate attention should be paid to ventilation and air filtration techniques in indoor spaces. This will help protect your indoor space in the future from this and other viruses that may occur.

“Covid-19 can be seasonal and you have to live with it just like the flu,” the researchers write. BMJ.. “Therefore, governments and health leaders need to pay attention to science and focus on airborne transmission. Vaccines that not only protect unvaccinated people and those who have failed, but can also appear at any time. A safer indoor environment is needed to thwart resistant mutants and new aerial threats. “

New research published in Lancet..

Source: University of Colorado at Boulder