Aerosol scientists say that the evidence points to airborne transmission of COVID-19 "beyond any reasonable doubt."
The organization's late March messaging, still available on social media, is a digital graphic saying, "FACT CHECK: COVID-19 is NOT Airborne".
Screenshot of WHO's Tweet from March 28, 2020 that is still published.
The petition asks for a course correct: "We, citizens of the world, request that the World Health Organization (WHO) recognize the compelling scientific evidence that SARS-CoV-2 spreads by aerosol transmission ("airborne") and urge the WHO to immediately develop and initiate clear recommendations to enable people to protect themselves."
In the vacuum of the WHO's inaction, aerosol scientists around the world scrambled to raise awareness of what they saw as a grave error.
"Almost immediately after that [March 28] announcement, we formed a group of 239 scientists from many countries and disciplines to convince them that they should acknowledge that there is airborne transmission, but we find that they are totally dead set against it," says Dr. Jose Jimenez, a chemistry professor at the University of Colorado at Boulder who has studied aerosols for 20 years. He supports the citizen petition.
In a letter to the WHO back in July, he and his colleagues wrote: "Studies by the signatories and other scientists have demonstrated beyond any reasonable doubt that viruses are released during exhalation, talking, and coughing in microdroplets small enough to remain aloft in air and pose a risk of exposure at distances beyond 1–2 m from an infected individual."
The scientists have also gone direct to the public with their findings: They published a comprehensive Google doc with detailed answers to many people's frequently asked questions about how to protect themselves, addressing issues ranging from the best masks and air filters to how to deal with passing someone outdoors and much more.
It's worth noting that the CDC has now modified its COVID FAQ to include airborne transmission as a "less common way" for the virus to spread. This update took place after the CDC stated in September that it is "possible" the virus spreads via airborne transmission – only to reverse course and remove the language from its website several days later. The CDC's website now states that some viruses, including SARS-Cov-2, "may be able to infect people who are further than 6 feet away from the person who is infected or after that person has left the space."
Basset Allen notes that after the scientists' open letter, the WHO "added ventilation to public communications about how to prevent infection, but they haven't explained why."
When contacted, a WHO representative had no specific comment and shared its late March announcement as well as its latest guidelines on transmission. In part, its statement says, "Current evidence suggests that the main way the virus spreads is by respiratory droplets among people who are in close contact with each other. Aerosol transmission can occur in specific settings, particularly in indoor, crowded and inadequately ventilated spaces, where infected person(s) spend long periods of time with others, such as restaurants, choir practices, fitness classes, nightclubs, offices and/or places of worship. More studies are underway to better understand the conditions in which aerosol transmission is occurring outside of medical facilities where specific medical procedures, called aerosol-generating procedures, are conducted."
A forceful and clear message acknowledging the evidence could make it easier to standardize school and office ventilation, petitioners argue.
Aerosol scientist Jimenez was dismayed by the WHO's response.
"The first part is an error in my opinion," he says. "Current evidence suggests that the main way the virus spreads is inhalation of aerosols.…WHO is way behind, unfortunately.
"The second part is incomplete," Jimenez continues. "Aerosol transmission can happen in those indoor crowded low-ventilation spaces. But if aerosols can accumulate under those conditions and cause infection, they must be extremely infective in close proximity when talking, since they are much more concentrated there. Just like talking close to a smoker you would inhale much more smoke (which is an aerosol) than if you were in the same room, but let's say 10 or 15 feet away."
He adds, "The WHO and others are making the assumption that if this goes through the air, then everyone who is infected is putting a lot of virus into the air at all times, but we know that's wrong: People are infectious for a short period of time before and during their symptoms. In China, they have measured how much virus comes out of people, and they see that the emission is sporadic: The virus can come out in millions of viral [particles] per hour, but it doesn't happen all the time."
The petition's co-creator, Basset Allen, says that her life experience showed her the best way to make a change. "My involvement with this effort is entirely personal," she says. "I was first introduced to HIV treatment activism as a college student and what I learned about campaigning and power has been relevant in almost every other project I've worked on since then. HIV activism taught me that everyday people can win big, life-saving policy changes if they build expertise and work strategically to push decision makers."
The petition and its advocates argue that the WHO's mixed messaging is causing real harm. For instance, a forceful and clear message acknowledging the evidence could make it easier to standardize school and office ventilation, they argue. Anecdotally, some schools have refused to install HEPA filtration in their classrooms due to a lack of specific guidance from health agencies. (Note: The CDC now recommends improving central air filtration and considering the use of portable HEPA filters in classrooms.)
As the holidays approach, a clear and unified message from all influential health agencies would also help people understand why it is still important to wear masks while physical distancing, especially indoors.
"Personally, I cheered when I heard President-Elect Biden mention ventilation upgrades in schools during the first 10 minutes of his October town hall event, and again in the second debate," Basset Allen says. "Unfortunately, we're still more than two months away from the Biden administration taking over the U.S. COVID-19 response and we have to do absolutely everything we can right now to save as many lives as possible. Increasing awareness of airborne transmission and mitigation strategies can't wait. WHO can use its power to help close that gap, here and around the world."
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Dr. Amesh Adalja, Senior Scholar, Johns Hopkins Center for Health Security and an infectious disease physician