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.
If that’s what the vaccine trials were measuring—the height of thewall that is our immune system comparing vaccine effectiveness would make a lot of sense. Many high-profile, highly-credentialed people have been (misleadingly) describing it exactly in that manner: that if a vaccine is 95% effective, those 5% are left “unprotected.” If Moderna and Pfizer and 95% efficacious, and if Johnson and Johnson is 66%—well, that would mean that 34% of the people are left “unprotected.” right?
Wrong. To get to why that assumption is not right—and why those vaccine efficacy numbers are not the height of the wall that represents the immune system—let me first mention something important The two mRNA vaccines do appear to be spectacular, but they were tested under conditions where those pesky “variants-of-concern”—the B.117 (UK one) and B. 1.351 (South Africa) and P1–were not widespread. If tested now, under equal conditions, those numbers may be closer. Plus, Johnson & Johnson is a single-shot with a trial with a booster underway. So those efficacy numbers may well be much closer in reality than they appear from the trial results. But let’s leave that aside for a moment.
Five key fallacies and pitfalls have affected public-health messaging, as well as media coverage, and have played an outsize role in derailing an effective pandemic response. These problems were deepened by the ways that we—the public—developed to cope with a dreadful situation under great uncertainty. And now, even as vaccines offer brilliant hope, and even though, at least in the United States, we no longer have to deal with the problem of a misinformer in chief, some officials and media outlets are repeating many of the same mistakes in handling the vaccine rollout.
Amidst all the mistrust and the scolding, a crucial public-health concept fell by the wayside. Harm reduction is the recognition that if there is an unmet and yet crucial human need, we cannot simply wish it away; we need to advise people on how to do what they seek to do more safely. Risk can never be completely eliminated; life requires more than futile attempts to bring risk down to zero. Pretending we can will away complexities and trade-offs with absolutism is counterproductive. Consider abstinence-only education: Not letting teenagers know about ways to have safer sex results in more of them having sex with no protections.