Virus World

Because of the fast-spreading Delta variant, health officials are renewing calls for people to wear face masks — even if they're fully vaccinated against COVID-19. Last week we told you that if anything looked likely to roll back our newfound pandemic freedoms, it was the Delta variant. Sure enough, it is. On Monday, the Los Angeles County Department of Public Health advised all residents to wear masks while they’re in public indoor spaces — even if they’re fully vaccinated against COVID-19.  It may seem like a mixed message. After all, the county reminded people that “fully vaccinated people appear to be well protected from infections with Delta variants.” And as far as scientists can tell, that appears to be true. But no vaccine is perfect. The county has confirmed at least 10 coronavirus infections involving the Delta variant among people who were fully vaccinated. None required hospital care, most likely thanks to the immune-system boost they got from the vaccine.

The Delta variant, which was first identified in India, has also been found in three county residents who were partially vaccinated and 110 who were unvaccinated. These are the people health officials are most worried about. Scientists estimate that Delta is 60% more transmissible than the Alpha variant from the United Kingdom, which in turn is 50% more transmissible than the original coronavirus strain. That means Delta spreads more than twice as readily as the version of the virus that sparked the global pandemic. Among coronavirus samples sequenced in the U.S. in the two-week period that ended June 5 (the most recent reporting period available), 10% were Delta, according to the Centers for Disease Control and Prevention. In the prior two weeks, this variant accounted for just 2.9% of samples sequenced.  In addition, by June 5, Delta made up nearly 35% of samples analyzed in Iowa, Kansas, Missouri and Nebraska, and 25% of those in Colorado, Utah, Montana, Wyoming and the Dakotas. In California, Delta accounts for 14.5% of coronavirus samples that have been sequenced so far in June, making it the third-most common variant in the state. With that in mind, asking everyone to wear masks in supermarkets, movie theaters, offices, retail stores and other indoor venues sounds like a way to be safe instead of sorry.

“Until we better understand how and to who the Delta variant is spreading, everyone should focus on maximum protection with minimum interruption to routine as all businesses operate without other restrictions, like physical distancing and capacity limits,” L.A. County officials explained in a statement. L.A.’s advice aligns with that of the World Health Organization, which advises people to “wear a mask, especially in crowded, closed and poorly ventilated settings,” even after they’ve been vaccinated. The CDC, on the other hand, still says people who’ve been fully vaccinated don’t need to wear masks or worry about social distancing. It’s unclear if Delta will prompt officials here to reinstate other safety measures for those who are vaccinated. Even if coronavirus spread accelerates, California’s vaccine coverage is high enough to prevent another devastating surge. (Contrast that with South Africa, where less than 1% of the population is vaccinated. The Delta variant is fueling a third wave of infections there that’s on track to top the previous two, prompting President Cyril Ramaphosa to impose a sweeping set of new restrictions that includes a ban on indoor and outdoor gatherings, earlier curfews for nonessential businesses and the suspension of leisure travel in and out of the country’s most populous province.)  But the more a virus spreads, the more chances it has to mutate. And the more it mutates, the more chances it gets to acquire a genetic change that reduces the efficacy of vaccines or medicines. “It’s quite simple: More transmission, more variants. Less transmission, less variants,” WHO Director-General Tedros Adhanom Ghebreyesus said Friday. “That makes it even more urgent that we use all the tools at our disposal to prevent transmission.”

Including masks.

Short of a total lockdown, universal mask-wearing is the most effective way to slow the relentless rise in hospitalizations and deaths from Covid-19.  As a professional health writer and concerned citizen, the ache in my heart deepens with each new report of the devastation wrought by the novel coronavirus, the cause of immeasurable — and still increasing — personal and economic pain for people caught in its deadly spikes. In a recent five-week period, 100,000 Americans died from complications of Covid-19, a toll that took the country four months to reach last spring. My distress is magnified by the knowledge that it didn’t have to be this bad. One simple measure — consistent wearing of face coverings in public — could have helped to stem the agony. In December, the Centers for Disease Control and Prevention reiterated advice first given in July: “Wear a mask over your nose and mouth. Everyone should wear a mask in public settings and when around people who don’t live in your household, especially when other social distancing measures are difficult to maintain.” Masks, the agency emphasized, protect both the wearer and those the wearer encounters in the course of daily life. Now, with the emergence of a highly contagious variant of the virus and the chaotic attempts to distribute and administer vaccines to hundreds of millions of vulnerable Americans, short of a total lockdown, universal mask-wearing is the most effective way to slow the relentless rise in hospitalizations and deaths from Covid-19.

It will take many months to immunize everyone willing and able to get a Covid vaccine. Meanwhile, we’re facing another tsunami of deadly coronavirus infections as the new variant sweeps through swaths of still-unprotected millions As with many other measures not taken by the last administration to minimize the spread of Covid-19, mask-wearing was left up to the states to mandate and enforce. Masks became a political football, and the former president publicly ridiculed opponents who wore them. Some elected officials even made the ridiculous, baseless claim that masks not only don’t thwart the spread of the virus, they actually enhance it. I wonder if they also ignored parents and teachers who told them to cover their mouths when they coughed or sneezed.  I also wonder about the economic savvy of our former president and the governors who have resisted issuing mask mandates, some of whom got Covid-19 themselves yet clamored to open the economy. Goldman Sachs estimated last June that implementing a nationwide mask mandate could have a potential impact on the U.S. GDP of one trillion dollars. Lately, as I await my second vaccine shot, I’ve become increasingly aware of how many people walk, run or cycle without a mask or, if they have a mask, wear it ineffectively. I’ve taken to speaking up more often: “Please wear your mask” or “The mask should cover your nose and mouth.” Among the ignorant responses: “I don’t need a mask when I’m outside,” “I already had Covid so I can’t get it again or give it to you,” and my favorite while walking on a four-foot-wide path, “I stay six feet away from people.” Although six-foot social distancing is not totally arbitrary, it’s based on limited evidence among airline passengers and may not apply at all, for example, to the unmasked cyclists shouting to one another as they ride past me or to the heavy-breathing runners I pass.

N95 masks should be wear while taking care of COVID-19 patients or sharing space or being in the proximity of  confirmed or suspected patients. Use of N95 mask may be recommended in small poorly ventilated public places where you expect to spend long period of times with other unknown persons, including public transportation. The decision to wear N95 masks in these scenarios should be based on the chances of contagion (e.g. expected number of infected people in the area), the risk factors of the user, and the discomfort of having to wear the mask for longer periods of time. N95 masks should not be wear outdoors or while doing exercise, unless the expectation of being in close proximity to infected persons is high. Universal use of common face masks (surgical masks) is more appropriate for outdoor environments.

The use of N95 mask increases the effort in breathing and may cause discomfort, tiredness or headache. As some people with chronic lung disease, heart disease or stroke may already have reduced lung volumes or breathing issues, they should stop using a N95 mask if they feel uncomfortable. They should consult their doctor as to whether they can use the N95 mask. The N95 mask is not suitable for pregnant women and children.Persons with chronic lung or heart conditions who feel uncomfortable when wearing the N95 masks should stop doing so and consult a doctor before carrying on.

Updated guidance from the US Centers for Disease Control and Prevention says people fully vaccinated against Covid-19 do not need to wear masks or practice social distancing indoors or outdoors, except in certain circumstances.

People fully vaccinated against Covid-19 do not need to wear masks or practice social distancing indoors or outdoors, except under certain circumstances, the director of the US Centers for Disease Control and Prevention announced Thursday. "If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic," Dr. Rochelle Walensky said during a White House Covid-19 briefing. "We have all longed for this moment when we can get back to some sense of normalcy."  Calling it an "exciting and powerful moment," Walensky said the science supports the updated CDC guidance that "anyone who is fully vaccinated can participate in indoor and outdoor activities -- large or small -- without wearing a mask or physical distancing." She cited three studies -- one from Israel and two from the United States -- that show vaccines work.  The Israeli study, which was published in the Journal of the American Medical Association, showed the vaccine was 97% effective against symptomatic Covid-19 and 86% effective against asymptomatic infection in over 5,000 health care workers. There have been reports of "breakthrough" infections among vaccinated people in the United States -- a small number among more than 117 million people in the United States who are now fully vaccinated. Walensky noted that "the resulting infection is more likely to have a lower viral load, may be shorter in duration, and likely less risk of transmission to others."

Mask wearing might also be reducing the severity of the virus and ensuring that a greater proportion of new infections are asymptomatic. Face masks may be inadvertently giving people Covid-19 immunity and making them get less sick from the virus, academics have suggested in one of the most respected medical journals in the world. The commentary, published in the New England Journal of Medicine, advances the unproven but promising theory that universal face mask wearing might be helping to reduce the severity of the virus and ensuring that a greater proportion of new infections are asymptomatic. 

The commentary, published in the New England Journal of Medicine, advances the unproven but promising theory that universal face mask wearing might be helping to reduce the severity of the virus and ensuring that a greater proportion of new infections are asymptomatic. It comes as increasing evidence suggests that the amount of virus someone is exposed to at the start of infection - the “infectious dose” - may determine the severity of their illness. Indeed, a large study published in the Lancet last month found that “viral load at diagnosis” was an “independent predictor of mortality” in hospital patients. Wearing masks could therefore reduce the infectious dose that the wearer is exposed to and, subsequently, the impact of the disease, as masks filter out some virus-containing droplets.  If this theory bears out, researchers argue, then population-wide mask wearing might ensure that a higher proportion of Covid-19 infections are asymptomatic. 

Better still, as data has emerged in recent weeks suggesting that there can be strong immune responses from even mild or asymptomatic coronavirus infection, researchers say that any public health strategy that helps reduce the severity of the virus - such as mask wearing - should increase population-wide immunity as well This is because even a low viral load can be enough to induce an immune response, which is effectively what a typical vaccine does. While this hypothesis needs to be backed up with more clinical study, experiments in hamsters have hinted at a connection between dose and disease. Earlier this year, a team of researchers in China found that hamsters housed behind a barrier made of surgical masks were less likely to get infected by the coronavirus. And those who did contract the virus became less sick than other animals without masks to protect them. Some observations found in humans seem to support this as well. In a coronavirus outbreak on a closed Argentinian cruise ship, for example, where passengers were provided with surgical masks and staff with N95 masks, the rate of asymptomatic infection was 81 per cent. This is compared with 20 per cent in earlier cruise ship outbreaks without universal masking.

Original Letter Published in NEJM (Sept. 8, 2020):

https://doi.org/10.1056/NEJMp2026913