Bahnfleth co-authors study examining delayed recognition of COVID-19 as airborne

September 19, 2022

Editor’s note: This article originally appeared on the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder website. It features William Bahnfleth, professor of architectural engineering at Penn State.

UNIVERSITY PARK, Pa. — In March 2020, both the World Health Organization (WHO) and the Centers for Disease Control (CDC) declared that the virus causing COVID-19 was not airborne and that to say so was spreading misinformation. In October 2020, after nearly a quarter of a million people in the United States had died from COVID, the CDC stated that the virus might have some airborne transmission. It took the WHO another year to come to a similar conclusion. William Bahnfleth, professor of architectural engineering at Penn State, joined colleagues from around the world to examine how past medical fallacies involving respiratory diseases may have contributed to this delayed reaction.

They published their study tracing the long history of rejecting airborne transmission theories, titled “What were the historical reasons for the resistance of recognizing airborne transmission during the COVID-19 pandemic?”, in Indoor Air. Bahnfleth and Jose-Luis Jimenez, lead author and professor of chemistry at Colorado University Boulder, co-authored the paper along with engineers, physicians, virologists, historians, public health specialists, aerosol scientists and a sociologist from 10 countries.

“In 2020, we received immediate and sustained advice from health experts that to prevent COVID-19 infection we should wash our hands, disinfect surfaces and install plexiglass barriers on the theory that short range, large droplet transmission and touching of contaminated surfaces were the main risks,” Bahnfleth said. “Meanwhile, little was being done to stop longer range transmission and the airborne virus was infecting people around the world for months before public health authorities acknowledged and began to act to mitigate airborne transmission.”

Bahnfleth and his colleagues examined similarly fatal — and preventable — instances throughout history of institutions and individuals misunderstanding root causes of public health crises, largely due to resisting and rejecting scientific evidence. According to Jimenez, the skepticism is honest and results from the challenge of shifting what people thought they knew.

The researchers also illuminated the deadly impact of “belief perseverance,” in which it can take years or decades to challenge a set of beliefs, especially when the consequence of changing a set of beliefs is expensive, both in terms of preventative action and in reputational harm. In the case of COVID-19, it costs far less to wash hands and disinfect surfaces than it does to update a ventilation system. Both WHO and CDC also had incentive to avoid backtracking on their initial statements and slow corrections, according to the paper.

Jimenez said that both honest skepticism and believe perseverance played a role in early 2020, as many people struggled to understand that conventional respiratory infection transmission — spreading through heavy droplets falling on surfaces — might not explain the prevalence of COVID-19 adequately.

“In an era of amazing scientific advances, with very rapid vaccine development following virus sequencing obtained in a few days, the very slow acceptance of critical new knowledge reminds us that the human aspects of science remain as pervasive as they were in past eras,” the researchers conclude in the paper.


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