US, WHO officials and experts agree (sort of) on how COVID-19 spreads

COVID: ‘We need to stop wearing cloth masks and go to N95s for all,’ expert says


Anjalee Khemlani
·Senior Reporter
Fri, April 8, 2022,

Sars-CoV-2, the virus that causes COVID-19, is airborne. That simple declaration from the White House is what some experts around the world have known since 2020 — and it could have major implications for U.S. businesses and organizations.

Dr. Alondra Nelson, head of the White House Office of Science and Technology Policy (OSTP) and deputy assistant to President Joe Biden, announced the highly-awaited words in a recent statement.

"The most common way COVID-19 is transmitted from one person to another is through tiny airborne particles of the virus hanging in indoor air for minutes or hours after an infected person has been there," she said.

That single sentence confirms what was first uncovered in a March 2020 report from the Centers for Disease Control and Prevention (CDC) and the National Institute of Allergy and Infectious Diseases (NIH) officials. However, that information was not relayed to Americans until several months later.

It took even longer for both the CDC and WHO to acknowledge COVID's spread via aerosols, despite growing evidence.

"SARS-CoV-2 remained viable in aerosols throughout the duration of our experiment (3 hours)" and was more stable on non-porous surfaces, the study said.

The latter point was emphasized by the Department of Homeland Security (DHS) a month later, without acknowledging the former. Eventually, the U.S. adopted the idea that transmission in the air was dominant, but through larger particles, or droplets, in the summer of 2020.

Why droplets were favored over aerosols has to do with the difference in the way aerosol experts and public health experts define the size of the particle. A tug-of-war between both sides made headlines in the first few months of the pandemic and have continued under the radar ever since.

U.S. President-elect Joe Biden listens to Dr. Alondra Nelson, his pick for OSTP Deputy Director for Science and Society (Reuters)
Why it matters

Deeming the coronavirus airborne places a burden on businesses, schools, and other indoor venues to ensure proper masking when COVID-19 levels are high in an area. In addition, it also presents the problem of revamping air systems or adding filtration and ventilation.

Marina Jabsky, an industrial hygienist with the New York Committee for Occupational Safety and Health, explained how to think about it.

"If you've ever been in the same room as somebody who's smoking, regardless of how far apart form them you're standing, you're gonna smell the smoke, right? Because the air particles will expand to fill the space," Jabsky said.

And size matters. The larger the space with fewer people in it, the lower the concentration is going to be.

"If you do not have a solid, well-functioning ventilation system, you're going to have a buildup of concentration of particles, and that's where the risk really increases," Jabsky said.

That's the reason behind the push for better quality masks, which the U.S. government has provided to Americans — via retail pharmacies and community health centers — for free. It's also why the American Rescue Plan (ARP) included $122 billion for schools and $350 billion for state, local and Tribal governments to help provide better ventilation systems.

One industry in particular was forced to quickly figure out how to keep its employees safe. After facing a shortage of personal protective equipment (PPE) at the start of the pandemic, hospitals are now able to regularly supply PPE to their staff. However, the cost of that PPE has gone up significantly compared to pre-pandemic levels.

Hospitals also adapted by either putting in better filtration systems, adding ventilation, or increasing the number of isolation rooms as needed. The steps to ensure filtration and ventilation came after it was discovered the virus was airborne.

"If it were droplet, and only droplets, then some of the masking requirements and some of the ventilation requirements might not be necessary," said Nancy Foster, vice president of quality and patient safety policy at the American Hospital Association.

Foster told Yahoo Finance that for droplets, proper masking is still be necessary, but some of the bigger facility upgrades might not be.

A person wearing a mask walks out of a store past a "Wear a face mask" sign, during the coronavirus disease (COVID-19) pandemic, in the Manhattan borough of New York City, New York, U.S., February 9, 2022. REUTERS/Carlo Allegri

'It doesn't make sense to completely remove the idea of droplets'

There is lingering pressure from some experts to maintain droplets as part of the definition of how the virus is transmitted. And that can impact the difference in which protective gear is used by health professionals.

Dr. Abraar Karan, an infectious disease doctor at Stanford, explained why.

He said droplets may not be the primary route, but they aren't excluded in the range of particle sizes.

Scientists have noted "both droplets and aerosols, and particles of sizes in between the two" hold the potential for spread, Karan said.

"People can still have larger droplets that land in their mucosa or land in other exposed areas. So it doesn't make sense to completely remove the idea of droplets," he said.

In a February interview with Yahoo Finance, CDC Director Dr. Rochelle Walensky didn't call it airborne, but noted Sars-Cov-2 was like any other respiratory virus and that masking and ventilation are essential to curb transmission.

Kim Prather, an aerosol expert at UC San Diego, is another expert who has consistently asked for widespread acknowledgement of airborne transmission, pointing to another coronavirus, SARS, noting it was airborne as well.

"One of the biggest lessons learned (then) was you've got to follow the precautionary principle. If you think it has any chance of being airborne, that has to be out there....whether it's the dominant (pathway) or not," she said.

OSTP's Nelson agreed, citing the CDC's latest definition of the spread of the disease that included "small droplets and aerosol particles that contain the virus."

It's why in her statement, Nelson included ways to cost-effectively upgrade air systems for businesses.

"We’re saying it more loudly now and with a unified voice across the federal government that the most important mitigation measures for restaurants and businesses are masking, distancing, and dilution or removal of COVID-19 virus particles in the air. These actions are more effective at reducing the spread of COVID-19 than sanitizing surfaces, which the CDC has said is not a substantial contributor to new infections," Nelson said.

But, according to Dr. Georgia Lagoudas, sanitizing is still a useful strategy.

"Over the past two years, we've had to deal with an evolving virus and learning new science," said Lagoudas, OSTP's Senior Advisor for Biotechnology and Bioeconomy.
How we got here

In April 2020, (the same day former President Donald Trump infamously suggested digesting disinfectant to get rid of COVID-19), DHS acting under secretary Bill Bryan said the virus could survive on surfaces for up to 18 hours in low humidity, low temperature environments.

The idea of aerosolized virus staying suspended for up to three hours wasn't discussed. Officials were mostly focused on symptomatic or asymptomatic spread, in addition to figuring out how to detect and curb transmission, as well as identify what substances break down the viral particles.

However, identifying aerosols became especially important after it became clear asymptomatic spread was occurring at a higher rate than expected. It's why masking was recommended soon after Bryan's presentation.

"Those two things have made the difference for this over every other disease process that we've seen in our lifetimes," said Dr. Joe Vipond, an emergency room doctor in Calgary, about asymptomatic and airborne spread.

"But neither of these changes, by the WHO or the CDC, were done in an open fashion," Vipond added.

Linsey Marr, an aerosol expert and professor of Civil and Environmental Engineering at Virginia Tech, noted the reliance on droplets missed the mark of how easily and effectively COVID-19 transmits.

Nelson used "strong, powerful, clear words that we should have heard from the CDC two years ago," Marr said.

Saskia Popescu, an assistant professor in the biodefense program at George Mason University, recently told Yahoo Finance the topic remains important.

"We definitely need to talk about aerosol transmission," she said.

"We need to make it very clear to people you can get infected by breathing it," Popsecu added.

Dr. Leyla Asadi, an infectious disease doctor, expressed a similar sentiment.

“I think that the word airborne is very straightforward. It gives you a really excellent mental model, you don’t need a complicated chart," she said.

Long-term benefits and lessons

Jose-Luis Jimenez, an aerosol expert and chemistry professor at the University of Colorado, has been one of the leaders of the effort to ensure global understanding of the virus's route of transmission.

He and Marr penned a recent op-ed highlighting the problem now is too many people will remember what they were first told — which was that the virus didn't spread far. This is why the combination of COVID-fatigue and politically-aligned resistance to mask use will remain an obstacle for ending the pandemic, they wrote.

However, the outlook isn't entirely grim. With the White House now behind the push, improving indoor air quality is a goal that can be worked toward beyond COVID.

It's "something we should be thinking about not just because of COVID, but because of general health," Popescu said.

There have long been studies showing those in urban or lower-income areas suffer from chronic health issues related to poor air quality. With upgraded air systems, that could improve overall health.

It’s a “chronic problem of not investing in infrastructure, not investing in ventilation,” NYCOSH's Jabsky said.

Prather noted, "We clean our water, we will not drink unfiltered water, but we will breathe unfiltered air. I mean, how does that make sense? We need cleaner indoor air."

Jabsky hopes the pandemic acts as a catalyst for the cause.

“At this point, if we’re having a global pandemic that is due to a disease that is airborne (and that is) not incentive enough to deal with our ventilation issues, I just don’t know what is going to be the stimulant,” she said.

Marr explained what's needed is an overhaul of regulations and standards.

"I think there's longer term changes, in terms of how we design and operate our buildings that we should be thinking about. And, ultimately, to put some teeth into this, there will need to be standards and regulations. And those will take years," she said.

Follow Anjalee on Twitter @AnjKhem