As the COVID-19 pandemic shows no signs of abating, and with the Omicron variant driving up the numbers worldwide, questions regarding the virus’s mode of transmission and the best practices in curbing its spread have been thrust into the limelight anew.
Is COVID-19 airborne?
Short answer: Yes
In its website, the World Health Organization (WHO) on Dec. 23, 2021, said current evidence suggests that a person can contract the virus when infectious particles that pass through the air are inhaled via a short-range aerosol or airborne transmission (interchangeable), or in a poorly ventilated and crowded indoor setting where aerosols can remain suspended in the air or travel farther than conversational distance via long-range aerosol or airborne transmission.
During the early days of the pandemic, however, the WHO on Mar. 29, 2020, declared as a “fact” that COVID-19 is “not” airborne, saying that it’s mainly transmitted through droplets generated when an infected person coughs, sneezes, or speaks, notwithstanding that there’s yet to be a strong evidence to make such a conclusive announcement regarding the novel disease at the time.
FACT: #COVID19 is NOT airborne.— World Health Organization (WHO) (@WHO) March 28, 2020
The #coronavirus is mainly transmitted through droplets generated when an infected person coughs, sneezes or speaks.
To protect yourself:
-keep 1m distance from others
-disinfect surfaces frequently
-wash/rub your ?
-avoid touching your ??? pic.twitter.com/fpkcpHAJx7
On Apr. 15, 2021, The Lancet, a United Kingdom-based peer-reviewed medical journal, argued that there are ten scientific reasons in support of airborne transmission of SARS-CoV-2, the virus that causes COVID-19:
- Transmission is much greater than indoors
- Transmission can occur between adjacent rooms
- Superspreader events best explained by airborne spread
- Non-coughing, non-sneezing people can still transmit
- Transmission occurs despite contact and droplet precautions
- SARS-CoV-2 has been detected in air samples
- SARS-CoV-2 has been detected in air filters and building ducts
- Transmission shown to occur via air duct in caged animals
- No strong or consistent evidence to refute airborne spread
- Limited evidence to support other routes of transmission
The United States Centers for Disease Control and Preventions on May 7, 2021, updated its science brief regarding COVID-19 to reflect such developments.
But as time went by, the WHO still hasn't made any reaction or announcement on what's what. It only acknowledged that airborne spread is a major route of COVID-19 infection as the year was about to end.
This drew the ire of Dr. Jose-Luiz Jimenez, a leading aerosol scientist and chemistry professor at the University of Colorado-Boulder, who criticized the organization’s decision as "one of the largest errors in the history of public health." When there has been growing evidence about COVID-19's airborne transmissibility, Jimenez said the WHO has been "avoiding saying it on purpose."
2/ I beg do differ. I think that decision by @WHO is one of the LARGEST ERRORS IN THE HISTORY OF PUBLIC HEALTH— Prof. Jose-Luis Jimenez (@jljcolorado) December 15, 2021
Let's compile evidence of how govts and organizations either don't know how to protect their citizens, or use @WHO's ambiguity to avoid doing so
Pls reply w/ examples!
Aside from journals and interviews, Jimenez has since taken it to Twitter to make his case as regards the virus's mode of transmission. In fact, he has had a debate with Dr. Ted Herbosa, National Task Force vs. COVID-19 adviser, after the latter questioned his expertise on the matter, saying the professor's announcements may not supposedly have validity in clinical practice.
Well, I just lead a peer-reviewed paper that demonstrates (with epi data from real outbreaks) that superspreading is due to shared-room airborne transmission:https://t.co/K5uB26xwng— Prof. Jose-Luis Jimenez (@jljcolorado) January 8, 2022
Still, Jimenez stood by his words, which gained the support of many netizens and even prompted a separate discussion on COVID-19's airborne transmissibility via Twitter Spaces, the platform's audio chat feature, led by Joshua Agar, a civil engineer specializing in wind dynamics.
What is the best way to deal with COVID-19 knowing it's airborne?
Short answer: Proper ventilation and better masks
Jimenez, in an interview with ANC last Jan. 7, likened the virus's spread to a cigarette smoke, which "mixes" in a room's atmosphere and can be inhaled by individuals inside.
With that, Jimenez said rooms must have enough ventilation, such as through open windows, to let the virus go out.
Agar, sharing an infographic summarizing the keypoints of the Twitter Spaces #CovidisAirbornePH, noted that in enclosed spaces, exhaust fans may be helpful in sucking air out. Ceiling fans, however, won't do as much as they won't push air out like usual electric fans do.
Summary of last night’s Twitter space on #CovidisAirbornePH— Joshua C. Agar (@JoshuaCAgar) January 10, 2022
Ten scientific reasons why Covid-19 is airborne by @trishgreenhalgh et al. (2021) in Lancet:https://t.co/NZoGrs1g6m
Below are the recommendations to reduce airborne transmissions (infographic by @mister_christer) pic.twitter.com/ubWeQZQI7z
Jimenez said that as much as possible, activities must also be done outdoors, where there's enough natural ventilation, as the chance of getting infected is "20 times less than indoors."
He also clarified misconceptions that the virus is living in the air that we breathe just because it's transmitted airborne.
"When you are in a box that is the room, that's trapping the air," Jimenez said. "It's phantasmagorical that it's gonna come from China and infect someone (elsewhere)."
If natural ventilation can't be helped, Jimenez suggested investing in high efficiency particulate air (HEPA) filters, which are used in vacuum cleaners and in industries which require high air quality.
An October 2021 study, which has yet to be peer-reviewed, suggests that HEPA air filters reduce risk from airborne pathogens.
During the severe acute respiratory syndrome, or SARS, outbreak in Hong Kong in 2003, the Hong Kong Hospital Authority had recommended the use of HEPA air filters to reduce virus transmission among health workers in facilities that had no isolation wards.
The Edmonton Public Schools in Canada have been planning to invest in the highest quality filters possible for each system in all of its 213 schools in a bid to curb COVID-19 transmission.
Northern Ireland is also mulling over installing filters, though an education department spokesman said the vast majority of their classrooms "already have adequate ventilation, noting that they "may be suitable where there is insufficient ventilation...but should never be used as a substitute for ventilation."
As for air purifier necklaces, whose prices range from P800 to P8,000, health experts including the DOH have since warned that there's no scientific proof that the gadgets work against airborne transmissions.
“The DOH does not recommend these these necklace purifiers,” DOH spokesperson Maria Rosario Vergeire said last August 2021. “While it is not harmful, it does not provide protection against COVID-19."
Air purifier company SmartAirFilters said that unlike big air purifiers that use HEPA air filters, air purifier necklaces use ionizers, which "make pollution stick to nearby surfaces, removing them from the air."
“But if the nearest surface is your body, there’s a problem,” SmartAirFilters said. "Your face, body and clothes act as the magnet for the pollution to stick to."
At the end of the day, however, Jimenez said the public must invest in "tight, effective" masks, citing the N95 respirator as example. Agar noted that it offers good filtering and breathability alike.
The N95 respirator is considered by experts as the most protective face covering you can get, as it filters out at least 95% of very small particles, like coronavirus.
Agar also added that double layering of masks, even with surgical and cloth masks, would also have good filtering, but may have low breathability.
World Health Network, a coalition of citizens and experts who are committed to global action to protect public health through progressive elimination of COVID-19, also published an infographic reiterating the best practices in dealing with the airborne COVID-19.
What measures are ineffective against an airborne virus?
Short answer: Face shields and plastic barriers
Jimenez also urged various countries to do away with outdated COVID-19 protocols. In particular, he gave the Philippine government a special mention for its implementation of face shields in dealing with an airborne virus.
"They (Philippine government) should invest their money on better masks and things that actually work," Jimenez said, noting that face shields are "basically useless," except if someone would cough on one's face directly.
In poking fun at the matter, Jimenez on Jan. 11 tweeted a photo of lawyer Larry Gadon taping his face mask to the inside of his face shield, with the hashtag #COVIDHallofHumor.
Back in June 2021, Agar decried the use of face shields. Agar said face masks and physical distancing would suffice in curbing the spread of the virus.
Re: face shields— Joshua C. Agar (@JoshuaCAgar) June 22, 2021
As a researcher who simulate wind flows, I am puzzled with the insistence on face shields.
Face shields causes intake of air to the regions beneath the shield to induce higher negative pressures.
Higher negative pressure, higher particulate transport.
In his research, Agar said small respiratory particles could still make their way inside the shield and accumulate near the face due to a negative pressure region it creates beneath the shield.
"Basically what the face shield is doing is you're becoming a vacuum cleaner," Agar told ANC in a previous interview. "When there's COVID in the air, you would be sweeping all the particles in the air base on the configuration on this face shield."
The national government only made face shields voluntary in areas under Alerts Level 1 to 3 in Nov, 15, 2021. The Department of Health (DOH), meanwhile, has since insisted that the policy is backed by science and expert medical opinion.
Jimenez has also since emphasized that plastic barriers do not actually block the particles, as they tend to go upward and still make it through the other side. He had criticized local schools for installing barriers, meriting a spot in his very own COVID Hall of Shame.
119S/ PHILIPPINES??: strange barriers in motorcycles to avoid transmission among riders. But limited trans. outdoors (https://t.co/RkLfvMFynC), mostly talking face-toface, nearly impossible when moving, esp. mask & helmet— Prof. Jose-Luis Jimenez (@jljcolorado) January 10, 2022
[I am told this is still in use]https://t.co/osP3WQfaHE pic.twitter.com/JlSIeB7vk0
I've had to add the Philippine schools to the World #COVIDHallofShame of the worst practices to fight COVID transmission— Prof. Jose-Luis Jimenez (@jljcolorado) January 5, 2022
COVID is Airborne, @WHO says it clearly now: https://t.co/tfehpqhUVa
Please start to follow Science: https://t.co/bl7lK8RH0ehttps://t.co/Pw2woYWFB9 pic.twitter.com/xMymLhndQA
Additionally, an August 2021 report by the New York Times had argued that plastic barriers “do little to stop the spread of the coronavirus.”
The report said plastic barriers can disrupt normal ventilation and create “dead zones” where viral aerosol particles can build up and become highly concentrated.
“If you have a forest of barriers in a classroom, it’s going to interfere with proper ventilation of that room,” Linsey Marr, professor of civil and environmental engineering at Virginia Tech, was quoted as saying.
In The Philippine STAR's report on Dec. 27, 2021, a study conducted by the Ateneo de Manila University, funded by the Department of Science and Technology, found that having fewer barriers in public transport vehicles reduces the risk of COVID-19 transmission.
“The study team also stressed the importance of wearing face masks that perfectly fit the face, instead of using barriers of any form that may also trap viral loads of SARS-CoV-2,” noted a report that cited the study.
Are other modes of transmission stil a cause for concern?
Short answer: They still are, but the focus right now must be on airborne transmission already
The WHO previously said that the virus can spread in small liquid particles through coughing, sneezing, speaking, singing, or breathing, as well as when people touch their eyes, nose, or mouth after touching surfaces or objects that have been contaminated by the virus.
But Jimenez has argued that at this point, airborne transmission is the "only important mode" of transmission that needs "100% of our efforts." He even called out the local DOH once for being "stuck on droplets," so much so that the major standing policy is still about plastic barriers and frequent washing of hands.
Jimenez also advised against using disinfectants on surfaces like Lysol and bleach, as the chemical components could actually do more harm than good.
"Surface transmission is not impossible, but it's not what we should focus on," he noted.
Dr. Edsel Salvaña of the DOH Technical Advisory Group, however, insisted in an phone interview with PhilSTAR L!fe that while there's "some airborne transmission in certain situations," respiratory droplets remain to be the "major transmission driver." He hasn't provided studies to substantiate this, but sent a link of a New York Times article dated July 7, 2020 when the WHO is still reviewing evidence of airborne transmission.
PhilSTAR L!fe also reached out to the DOH to shed more light into the matter, but they have yet to respond.