The World Health Organization (WHO) announced changes to its guidelines on Friday about who should wear a mask during the Covid-19 pandemic and where to wear it.
The new guidance recommends that the general public wear cloth masks made of at least three layers of fabric “on public transport, in shops, or in other closed or crowded areas.” It also states that people over 60 years of age or with pre-existing conditions should wear medical masks in areas where transmission of the coronavirus by the community and physical distance is impossible, and all workers in clinical environments should wear medical masks in an area of widespread transmission.
It is a major update from the agency 6 April recommendations, which stated that members of the general public “should only wear a mask if you are caring for someone with Covid-19” or “if you are coughing or sneezing.”
At one WHO press conference on June 3, Michael Ryan, an infectious disease epidemiologist and the executive director of the WHO’s health emergency program, said WHO still believes that masks should be used primarily “for source control – in other words, for people who may be contagious, reduce the chance that they will infect someone else. ”
And on Friday, WHO Director General Tedros Adhanom Ghebreyesus offered a few warning words as part of the announcement: “Masks can also create a false sense of security, causing people to ignore measures such as hand hygiene and physical distance. I can’t say this clearly enough: masks alone won’t protect you from Covid-19. ‘
But the changes are finally aligning the WHO with many countries around the world that have made masks mandatory in crowded public spaces, including Cuba, France, Cameroon, Vietnam, Slovakia, and Honduras. While masks are not a requirement, the U.S. Centers for Disease Control and Prevention (CDC) has since April 3 suggested “Wearing fabric face covers in public institutions where other social distance measures are difficult to enforce.”
Many health experts have wondered why it took so long for WHO to update the guidelines for masks, given the accumulation of evidence that they can be useful and have few drawbacks.
Eric Topol, research method expert and director of the Scripps Research Translational Institute, calls the WHO’s delay “ridiculous.” He adds, “I have a lot of respect for the World Health Organization, but they have completely misunderstood the mask story and we lost people because of it.” Lawrence Gostin, director of the O’Neill Institute for National and Global Health Law at Georgetown University, agrees, saying, “Everyone should wear a mask.”
This is what the research suggests and why experts believe the WHO has now revised the guidelines.
Why wear a mask?
The WHO did not name any specific research because of the dramatic change, just noticing that it “developed this guidance through a careful assessment of all available evidence and extensive consultations with international experts and civil society organizations.”
But there have been a number of recent studies that experts cite as the best evidence of masking use among the general public to reduce Covid-19 transmission. And a growing number doctors, scientists, and public health experts advocate universal masking in public indoor areas and crowded outdoor areas.
One meta review published in Lancet browsed 172 studies on Covid-19, SARS and MERS, from 16 countries and six continents. The authors found that masks – as well as physical distance and eye protection – helped protect against Covid-19.
The studies examined the evidence in both healthcare and non-healthcare settings and then adjusted the data for immediate comparison. The researchers found that your risk of infection when wearing a mask was 14 percent lower than if you weren’t wearing a mask, although N95 masks “ may be associated with greater risk reduction ” than surgical or fabric masks.
Other literature reviews were not so favorable. Paul Hunter, a professor of medicine at the University of East Anglia and one of Covid-19’s infection prevention advisory bodies, co-authored such prepress review in early April. “In evidence-based medicine, randomized controlled trials should outperform observational studies,” he says, “and randomized controlled trials have all been quite negative for face masks in the community.” The Lancet piece, he notes, pays more attention to observational studies using surgical masks.
Some recent observational studies of public use of masks in this pandemic support the general use of masks to prevent the spread of Covid-19. One from Hong Kong concluded, “mass masking in the community is one of the main measures controlling transmission during the outbreak in Hong Kong and China.” Another concluded that if 80 percent of a population that would wear masks, the number of Covid-19 infections would decrease by a 12th, based on observations from different Asian countries where wearing masks is common.
There has been some debate about the efficacy of homemade fabric masks and surgical masks (especially compared to N95 masks, which have more evidence behind them) to the general public. But a recent article, published in the Annals of internal medicine, discovered that even fabric masks prevent some viral particles from escaping.
The general consensus is that masks are better at preventing your viral particles from spreading to others than from someone else spreading to you. Catherine Clase, the lead author of the Annals of internal medicine piece, says that in a study she reviewed, even a single layer of cotton tea towel tested against a virus aerosol reduced virus transmission by 72 percent. “One thing to remember,” she says, “is that a mask doesn’t have to be perfect” to reduce the average number of people infected by one sick person. “It should only reduce the chance of transmission to some extent.”
William Schaffner, an infectious disease specialist at the Vanderbilt University Medical Center, notes that previous data on masks and viruses came from the SARS and MERS epidemics, which involved viruses that were not so transmissible. “Masks were then considered more personal protection than community protection,” he said, explaining why masks were not generally considered to be particularly effective.
But with Covid-19, the number of asymptomatic patients can be as high as 40 percent, which required a change in thinking about masks, from protecting the wearer to protecting the community. And so Clase concludes that while cloth masks may not protect you from inhaling other people’s germs, “evidence that they reduce contamination [from sick people] of air and surfaces is compelling and should be enough to inform policy decisions about its use in this pandemic. ”
Clase adds: “The pandemic is not going very well. So this is probably worth using now and doing the additional research later. ”
Why WHO may have struggled to reach an agreement on universal masking
Overall, WHO conducts very thorough assessments of evidence, as the health of the world is based on their recommendations. This may explain their delay in recommending masks to the general public.
In the past, the agency based its decisions largely on expert advice, Hunter says. “They would put together a group and they would use these experts to guide WHO guidelines.” But in 2007 a Lancet paper criticized the agency for not following evidence-based medicine, which prioritizes randomized controlled trials.
As a result, Hunter says, “WHO has seen a major upheaval in its guideline development practices. Now it should base its recommendations on systematic reviews ”, and each guideline committee now has methodologists.
“I think [the delay] reflects a general principle often followed by scientists, namely not to change the practice until the evidence is strong and definitive, ‘Trish Greenhalgh, a professor of primary care science at Oxford University, wrote in an email responding to questions. “While many people (myself included) believe that this is already the case, some scientists in WHO committees have been waiting for additional evidence to reinforce the case.”
Greenhalgh argued in early April that it was time to apply the precautionary principle to the pandemic response and that the public should wear masks “because we have little to lose and may have something to gain.”
But David Heymann, professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine and member of the WHO’s Strategic and Technical Advisory Group for Infectious Hazards (STAG-IH) advisory board, says the service is “very careful not to use to make evidence when we have it. We don’t take precautions if we don’t have any supporting evidence. “
STAG-IH itself was asked in early May to investigate the evidence for and against mask use and stated one report for the WHO that was made public on May 25. The finding “supports the use of masks by the general public in the community to reduce the risk of infection,” the WHO said in a statement to Vox and noted that when updating their guidelines, they followed the STAG-IH advisory consideration.
Cliff Lane, the clinical director of the National Institute of Allergies and Infectious Diseases at the National Institutes of Health and another member of STAG-IH, says WHO is’ very good at trying to get a diverse set of opinions before making recommendations’. But he admits he doesn’t know why the WHO has so timed its recommendations for masks.
He is one of many experts interviewed by Vox who noted that it is difficult to conduct a randomized, double-blind controlled study of mask use among the general public. Because of ethics and usefulness, “much of the epidemiological data on impact is derived,” he says. This adds to a general problem he sees: “Every guideline you create assesses the risks and benefits, and you want to get as much information as possible.” For example, if wearing a mask gives a sense of false security and encourages people to quit social distance, the consequences may not be worth it. “It’s not a trivial decision,” he says.
Heymann says the delay in the WHO recommendation is partly due to the need to take into account evidence from around the world. “WHO takes longer because there is a need for consensus from global experts and to inform six regional offices.”
Hunter added that nation-states can make partial decisions based on political or informed guesses. “But WHO cannot make such political decisions. It should try to get a consensus among scientists, because people look to WHO to make decisions where possible based on hard evidence. ”
As Heymann sees it: ‘WHO is just the gold standard. Countries are often ahead of WHO – they don’t have to wait for WHO to make recommendations. “
Topol, on the other hand, says the best reason he can think of for the WHO not everyone recommends wearing masks is because of concerns about a global shortage of masks, especially in the US. He may say, “They didn’t want to have badly distributed masks because of the urgent need and lack of personal protective equipment for medical personnel.”
But, he adds, “That’s not the reason for saying you don’t need masks – that’s the reason for saying we need to make masks urgently.”
“The world needs WHO – and it needs it now more than ever”
The WHO has been under scrutiny since the pandemic began. And it just got worse recently: late May, President Trump announced that the US would withdraw from WHO altogether, potentially withdrawing a significant portion of the agency’s funding.
But the WHO isn’t the only one slow with the use of masks. Countries like Venezuela made masks mandatory on March 14 and the Czech Republic made the switch 18th of March. But the US CDC originally recommended masks for the public, only changing its guideline into universal masking April 3rd.
Richard Besser, president of the Robert Wood Johnson Foundation and former acting director of the CDC, explains that during an emergency, experts should look at new information and evaluate decisions. He led the emergency planning and response at the CDC for four years, saying, “When counseling went up, it was always interim. What you don’t know at first always exceeds what you do know, and as you learn more, you make changes. “
Sometimes those changes are small and sometimes, as in the case of the CDC mask guidance, significant. “To make that logical to the public, you need something we don’t have right now: direct communication,” said Besser. “That is valuable because it gives confidence in crisis situations, where people have to do things to protect their health. They will do them much more often if they trust the messenger.”
Unlike the CDC, it has been outright criticized Due to the lack of press conferences, the WHO continues to hold daily daily conference calls during the pandemic.
“The WHO, like the CDC, is far from perfect, and is flawed in many ways,” says Gostin. “After working with WHO for 30 years, I can say that they can be insanely bureaucratic and unresponsive. But the world needs the WHO – and it needs it now more than ever. ‘
Lois Parshley is a freelance investigative journalist and the Snedden Chair of Journalism 2019-2020 at the University of Alaska Fairbanks. Follow her Covid-19 report on Twitter @loisparshley.