Can Loud Talking Spread Coronavirus?
Sneezing and coughing can spread Covid-19. But what about talking, singing, chanting, and yelling? Here's what medical experts know so far.
There’s still a lot we don’t know about Covid-19, but one thing is certain: It spreads like wildfire. Several states, including Arizona, Florida, and Texas, are reporting record-high levels of new Covid-19 cases. The full tally in the United States now stands at more than 2.6 million infected, although the Centers for Disease Control and Prevention (CDC) believes the true number is much higher, with CDC director Robert Redfield estimating 5 percent to 8 percent of the population has been infected.
One of the most important things to understand about the virus is how it spreads. Just like the flu, the new coronavirus can spread via sneezing and coughing. But some experts also worry that you can catch Covid-19 from someone talking, singing, shouting, or even just breathing heavily. “All the research is very, very new,” says Teresa Murray Amato, MD, chair of emergency medicine at Long Island Jewish Forest Hills in Forest Hills, New York. “We’re learning how to fly the plane while building it at the same time.”
Here’s what we know so far about how the virus itself flies—literally—between people and whether talking, especially loudly, to others, can really increase the risk of infection.
Getty Images (2), thehealthy.com
Covid-19 spreads from person to person
At the most basic level, experts believe that Covid-19 passes primarily between people who are in close contact with each other. As a respiratory virus, it lodges in the back of the throat and behind the nose then burrows into the bronchial tubes which lead to the lungs, explains William Schaffner, MD, an infectious disease specialist at Vanderbilt University Medical Center in Nashville. A cough or sneeze from an infected person propels the virus, which hitches itself to respiratory droplets, into the air. Covid-19 is most easily transmitted when two people are within six feet of each other and inside, even if a person has no symptoms, a March 2020 study in Science China Life Sciences shows. Touching a contaminated surface then touching your eyes, nose or mouth can also spread the virus, though probably not as much. “To the best of our knowledge, these are the only two ways you can get infected with the virus,” says Greg Poland, MD, an expert for the Infectious Diseases Society of America (IDSA). (Here are 12 symptoms of Covid-19 you should watch for.)
Respiratory droplets vs aerosol particles
Experts are now trying to figure out whether the virus spreads through respiratory droplets alone, or respiratory and aerosolized droplets. What’s the difference? Respiratory droplets are bigger and heavier than aerosolized particles so gravity pulls them earthward quickly, minimizing the time you could be exposed. Aerosolized particles, on the other hand, are smaller and lighter and float around for longer and travel farther, making them potentially infectious for longer, according to a March 2020 study in the New England Journal of Medicine (NEJM).
“Think of it as a sliding scale based on droplet size,” says Dr. Poland, who is also a professor of medicine and infectious diseases at the Mayo Clinic in Rochester, Minnesota, director of the Mayo Vaccine Research Group and editor-in-chief of the journal Vaccine. “The larger the droplet, like if I cough or sneeze, those generally fall out of the air in about six to 10 feet or less. Models show that aerosolized particles will spread in a cloud of about 27 feet and linger in the air not for a minute or two but for 30 minutes or so.” An April 2020 NEJM study recorded that SARS-CoV-2 (the virus that causes Covid-19) aerosol bits stayed viable in the air for three hours, although its infectiousness did decrease. (Here’s what you should know about virus super spreaders.)
So, does talking pose a risk?
We know that coughing and sneezing can transmit the Covid-19 virus, but can talking also launch the virus into space? Possibly but, like so many other things around Covid-19, we don’t know for sure, says IDSA spokesperson Ravina Kullar, a doctor of pharmacy. Researchers publishing in the Proceedings of the National Academies of Sciences (PNAS) used laser light scattering to picture particles produced when a person uttered “Stay healthy,” at three different volumes. (You can see the video here; by the way, stay tuned for the person saying the phrase again while wearing a mask—the difference in the spread of droplets is remarkable.) Droplets were expelled at all three volumes, but the louder the person spoke, the more particles they emitted and the greater the spread.
What’s more, the droplets stayed in the air for anywhere from three to 14 minutes, points out Dr. Kullar. What we don’t know is whether all those droplets from speech actually translate to infectious risk, she points out. People who enter a room after someone with measles has occupied the space can still get sick. That’s because the aerosol particles linger in the air. “We’re not seeing the same story for SARS-CoV-2,” she adds. “That’s what’s making scientists wonder is it a respiratory or aerosol phenomenon.”
The PNAS study reported that covering the face with a damp washcloth effectively prevented the particles from escaping. (Here’s what doctors need you to know about coronavirus face masks.)
What about singing?
Talking (especially talking loudly) and singing along with cheering, chanting, and yelling are all variations on the same theme, points out Dr. Schaffner, who has fielded calls from music teachers wondering if they can resume choral singing classes. “It’s pretty standard stuff,” he says. “When you’re yelling or singing, obviously you’re exhaling with more vigor, giving it literal energy, and you’re throwing your exhalation out a greater distance and literally bringing up more virus.”
There is plenty of research suggesting that singing can, indeed, spread the virus. One of the earliest examples was that of a choir practice in Washington State. Sixty-one people practiced together on March 17 for two-and-a-half hours. One infected person with symptoms infected at least 32 individuals; another 20 people may have also contracted Covid-19 from this person. Three went into the hospital, two died.
Experts are also concerned about contact sports: “You’re breathing deeply and you’re close to each other,” says Dr. Kullar. (Find out why some people are more likely to spread Covid-19 than others.)
Is it safer to be inside or outside?
All evidence so far points to being safer outdoors. “The virus spreads most easily if you’re together for prolonged periods of time in an enclosed space,” says Dr. Schaffner. “If you’re outdoors and the breezes are blowing, there’s more dilution and it doesn’t spread as readily. The vast amount of transmission occurs within a space of six feet.”
Other outdoor environmental factors also play into it. Higher temperatures and vapor pressure along with UV light and are bad for the virus, good for you. In general, the higher the temperature, the shorter the “life” span of the virus, explains Dr. Poland (although viruses aren’t technically alive).
Protests and coronavirus risk
One reason why experts are less concerned about the Black Lives Matter protests contributing to infections is that the events have taken place mostly outdoors. No spikes yet recorded from the protests, as reported by a June 2020 analysis of cell-phone data by the National Bureau of Economic Research. The authors speculate that this was due at least partly to more people staying at home after the protests. “We do think that the outdoors gives you some sort of protection but that’s no guarantee,” says Dr. Murray Amato. (You may want to know how safe it is to walk outside during the pandemic.)
Wear a mask
As the previously mentioned PNAS study shows, wearing a face covering is important. “It’s able to capture some of those particles and block them from being transmitted,” says Dr. Kullar. According to Stanford University, respiratory droplets which are larger evaporate into the smaller aerosolized particles. Masks catch the droplets before they evaporate and become potentially more dangerous particles.
Mask-wearing is also recommended by the CDC, especially in tight spaces and larger crowds. A June 2020 study in Health Affairs found that mask-wearing in 15 states where it was mandated prevented as many as 230,000 to 450,000 Covid-19 cases. Mask-wearing is critical with continuing protests, upcoming elections, and more bar and restaurant traffic in some parts of the country.
“Viruses use human nature and human nature is to be together,” says Dr. Murray Amato. “We have to find ways to trick or outsmart the virus. Right now, we don’t have a cure. The only thing we can really do is modify our behavior.
How best to use your mask
Stanford University recommends not sharing your face mask and keeping it protected when you’re not using it (maybe in a Ziploc bag). “Charging your mask may also make it more effective.” Stanford scientists rubbed different types of fabric—cotton, polyester, polypropylene, nylon, and silk—with latex gloves for 30 seconds and found that this increased their protection by as much as 30 percent for several hours.
The question of whether the Covid-19 virus can spread through aerosolized particles is still in the realm of the theoretical. For now, advises Dr. Schaffner, focus on what’s important—which is that Sars-CoV-2 can spread through respiratory droplets. And wearing masks will minimize that risk. (Here are 19 coronavirus myths you should stop believing.)
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- Washington Post: "CDC chief says coronavirus cases may be 10 times higher than reported"
- Centers for Disease Control and Prevention: "Transcript for the CDC Telebriefing Update on COVID-19"
- Teresa Murray Amato, MD, chair, emergency medicine, Long Island Jewish Forest Hills, in Forest Hills, New York
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- William Schaffner, MD, an infectious diseases specialist at Vanderbilt University Medical Center in Nashville
- Science China Life Sciences: "Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China"
- Greg Poland, MD, expert, Infectious Diseases Society of America
- New England Journal of Medicine: "Droplets and Aerosols in the Transmission of SARS-CoV-2"
- NEJM: "Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1"
- Ravina Kullar, PharmD., spokesperson, Infectious Diseases Society of America and adjunct faculty, UCLA David Geffen School of Medicine
- Proceedings of the National Academies of Sciences: "The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission"
- NEJM: "Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering"
- Morbidity and Mortality Weekly: "High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice — Skagit County, Washington, March 2020"
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- Health Affairs: "Community Use Of Face Masks And COVID-19: Evidence From A Natural Experiment Of State Mandates In The US"