Why did it take so long to accept that SARS-CoV-2 was being transmitted through aerosols, respiratory particles that are small enough to remain suspended in the air, rather than through short-range respiratory droplets that could not travel more than a few feet because of their (bigger) size?
The reasons for this delay go back more than a century, to the fight against (incorrect but prevalent) theories that blame miasma—noxious odors, especially from rotting organic material—for diseases. While trying to counter erroneous but millenia-long folk-beliefs, some of the founders of public health and the field of infectious control of diseases around the world made key errors and conflations around the turn of the 20th century. These errors essentially froze into tradition and dogma that went unchanged and uncorrected for more than a century, until a pandemic forced our hand.
But clear evidence doesn’t easily overturn tradition or overcome entrenched feelings and egos. John Snow, often credited as the first scientific epidemiologist, showed that a contaminated well was responsible for a 1854 London cholera epidemic by removing the suspected pump’s handle and documenting how the cases plummeted afterward. Many other scientists and officials wouldn’t believe him for 12 years, when the link to a water source showed up again and became harder to deny. (He died years earlier.)
Similarly, when the Hungarian physician Ignaz Semmelweis realized the importance of washing hands to protect patients, he lost his job and was widely condemned by disbelieving colleagues. He wasn’t always the most tactful communicator, and his colleagues resented his brash implication that they were harming their patients (even though they were). These doctors continued to kill their patients through cross-contamination for decades, despite clear evidence showing how death rates had plummeted in the few wards where midwives and Dr. Semmelweis had succeeded in introducing routine hand hygiene. He ultimately died of an infected wound.
In testimony before US Congress on March 11, 2020, members of the House Oversight and Reform Committee were informed that estimated mortality for the novel coronavirus was 10-times higher than for seasonal influenza. Additional evidence, however, suggests the validity of this estimation could benefit from vetting for biases and miscalculations. The main objective of this article is to critically appraise the coronavirus mortality estimation presented to Congress. Informational texts from the World Health Organization and the Centers for Disease Control and Prevention are compared with coronavirus mortality calculations in Congressional testimony. Results of this critical appraisal reveal information bias and selection bias in coronavirus mortality overestimation, most likely caused by misclassifying an influenza infection fatality rate as a case fatality rate. Public health lessons learned for future infectious disease pandemics include: safeguarding against research biases that may underestimate or overestimate an associated risk of disease and mortality; reassessing the ethics of fear-based public health campaigns; and providing full public disclosure of adverse effects from severe mitigation measures to contain viral transmission.
Author(s): Ronald B. Brown
Publication Date: 12 August 2020
Publication Site: Cambridge University Press Public Health Emergency Collection