COVID: While the world sanitized surfaces, a group tried to warn early on about airborne spread

Woman coughing into hand

RollingCamera / iStock

A large group of experts from around the world say they warned the World Health Organization (WHO) at the start of the COVID-19 pandemic that SARS-CoV-2 spreads through airborne particles, but their concerns weren't acknowledged until 3 months later, according to an account published late last week in Clinical Infectious Diseases.

The group says that, on Feb 7, 2020, Junji Cao, PhD, from the Chinese Academy of Sciences told Lidia Morawska, PhD, of Queensland University of Technology in Australia that he worried that authorities might not recognize the risk of aerosol SARS-CoV-2 transmission. Aerosols are tiny virus-laden particles expelled through the mouth and nose that can travel long distances on air currents.

Unheard voices, a tweet of denial

The two aerosol experts wrote a commentary calling for acknowledgement and communication of the risk, but two influential journals rejected it, saying authorities already knew how SARS-CoV-2 spread. Two months later, Environment International published the article.

After the WHO emphatically tweeted on Mar 29 that COVID-19 doesn't spread through the air, Cao and Morawska assembled an expert group to convince the WHO otherwise. The group was made up of 36 experts with a background in airborne transmission from the fields of aerosol physics, virology, public health, clinical medicine, infection prevention and control, building engineering, and facility management.

On Apr 1, the experts, known as Group 36, sent a petition to WHO Director-General Tedros Adhanom Ghebreyesus, PhD, and his management team in the Health Emergencies Program. Program staff sent a written response on Apr 16 maintaining that airborne SARS-CoV-2 spread was mainly limited to aerosol-generating procedures such as intubation.

A turning point

Group 36 then engaged more experts in supporting a commentary published on Jul 6 in Clinical Infectious Diseases. At a press conference the next day, the WHO acknowledged that SARS-CoV-2 spreads through aerosols. The WHO, however, didn't directly connect "ventilation" with "airborne transmission," which Group 36 authors said failed to convey sufficient warning to national authorities or the public on the importance of good ventilation.

Morawska and colleagues said that 3 months from warning to acknowledgement might not seem very long in the context of the pandemic, but "Those early 3 months were critical, because this was when control measures were being developed and introduced in countries around the world. This was also the time when public interest was most acute and messages around transmission were embedded into the actions that millions of people took in their daily lives."

In addition, it wasn't until May 2021 that the WHO changed its web page on COVID-19 transmission to acknowledge airborne spread. Before that, it had said, "Current evidence suggests that the main way the virus spreads is by respiratory droplets among people who are in close contact with each other." The US Centers for Disease Control and Prevention followed suit in changing its guidance shortly thereafter to emphasize airborne transmission more.

This was also the time when public interest was most acute and messages around transmission were embedded into the actions that millions of people took in their daily lives.

Group 36 was a leading voice warning about airborne spread early in the pandemic but not the only one. In November 2022, as WHO Chief Scientist Soumya Swaminathan, MBBS, MD, a speaker at the WHO's Jul 7, 2020, press conference, announced her departure from the agency, she said the WHO's decision to delay acknowledgement of the role of aerosols in SARS-CoV-2 spread was her biggest regret.

"We think that this account should be made public to serve as a warning about what happens when scientific evidence is rejected in favour of beliefs that have become dogma without a firm evidence base," Group 36 wrote in the new paper. "One can say that these disturbing events are in the past; let's move on. Yet the consequence of this 'past' was the loss of many lives, along with huge economic consequences."

This week's top reads