The “most comprehensive study to date” found that physical distance and perhaps the use of a mask were the two best ways to prevent transmission of the new coronavirus.
The new study, published in the medical journal Lancet on Monday, found that people should be at least one meter away and more if possible.
The review of various published studies, funded by the World Health Organization, had three main results:
The researchers examined 172 observational studies in 16 countries and six continents, including health and community studies. They did not examine randomized controlled trials, considered the gold standard but almost impossible to implement to study the transmission of infections in people.
Researchers from universities around the world analyzed studies of the outbreaks of Covid-19, the severe acute respiratory syndrome virus of SARS and the Middle East respiratory syndrome virus (MERS), which belong to the same virus family.
‘Big step forward’
The results of the review support a physical removal policy of at least 1 meter (3.3 feet) and, if feasible, 2 meters (6.6 feet) or more, the researchers said. The information could also be used to inform patterns that predict the spread of the disease and help with contact tracking schemes, added the research team, led by Holger Schünemann of McMaster University in Canada.
Trish Greenhalgh, a professor of primary health care services at the University of Oxford who was not involved in the research, said that while all of these findings were subject to uncertainty, the overwhelming message is that physical measures are effective in preventing Covid. -19.
“This is a big step forward in our knowledge, since the previous meta-analyzes were mainly based on the prevention of influenza and other diseases, which do not behave in the same way as the Covid-19 virus,” he told the Science Media Center from London.
“In all three questions, the evidence seems to support the measures. For example, on average, staying 1 meter away from other people seems to reduce the chance of catching Covid-19 by 80%. Wearing a mask or cover for the face it seems to reduce risk up to 85%. Wearing glasses or a face mask seems to reduce it up to 78%. “
WHO spokesman Tarik Jašarević said the international health agency is updating its advice on the use of masks, with a change that is likely to be announced this week.
The changes are likely to touch the best materials to make homemade masks, based on recent US data, “he told CNN via email.
“WHO has continued to focus on the use of masks where there is evidence that may limit transmission, such as in healthcare facilities. Indeed, the new guide could expand their use in these settings,” he added.
The next steps for government leaders
The key question now was how governments and the public should interpret these findings, said Linda Bauld, a professor of public health at the University of Edinburgh.
“The first and probably the most useful result is that physical distance is important. There have been many complaints that driving in the UK 2 meters away is excessive because it is more than in other countries,” he told Science Media Center.
“But this review supports it. Maintaining this distance will likely reduce your risk compared to 1 meter. Therefore, where possible, this is the distance that retailers and employers should use when multiple premises and workplaces reopen in the future.”
Bauld added that although the certainty of the evidence was poor on face masks, making it more difficult for governments to make them mandatory, the review added to the evidence that leaders should ask the public to wear face coatings on public transportation, in stores and other interior spaces even when physical spacing is in place, he said.
For healthcare professionals, the study found that N95 masks and other respiratory masks could offer greater protection from viral transmission than surgical masks or multi-layer cotton or gauze masks.
The review, however, did not examine the effects of the mask worn to protect other people, Greenhalgh of Oxford noted. He said the public should wear a cloth mask or standard surgical mask, leaving respiratory masks for healthcare professionals.
Even if used and combined correctly, the distances, masks and eye protection do not offer complete protection, the study pointed out and basic measures such as hand washing are essential to reduce transmission.
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