Surfaces were the item to be concerned about in the early days of the pandemic. The coronavirus was thought to transmit mostly by huge droplets that fell onto surfaces, which we then touched with our hands, which we then contacted our faces with. (At the time, public health officials claimed that masks were unnecessary for the general public.) As a result, we cleansed our hands till they were raw. We twisted our bodies to avoid touching doorknobs. We used a lot of hand sanitizer, hit elevator buttons with keys and pens, and sterilized our groceries, takeout orders, and mail.
Then we realized we'd done everything backwards. The virus transmitted primarily through the air rather than through surfaces. We learned about the dangers of enclosed spaces, the significance of ventilation, and the distinction between a cloth mask and a N95 mask. Meanwhile, we largely ceased discussing hand-washing. The days of hearing folks humming "Happy Birthday" in public restrooms are long gone. Wiping down packages and flamboyant workplace-disinfection measures become a form of hygiene theater.
This entire episode was one of the pandemic's strangest and most perplexing swings. Sanitation, the great pillar of public health, saved lives; however, it had little effect on COVID. On one level, this reversal should be viewed as a sign of excellent scientific progress, but it also calls into question the kinds of actions we previously felt were our best available defense against the virus. How vital is hand-washing if it isn't as important as we thought it was in March 2020?
Any public-health professional will tell you that, yes, you should still wash your hands. Emanuel Goldman, a microbiologist at Rutgers New Jersey Medical School, calls it "commonsense hygiene" for safeguarding us from gastrointestinal infections transferred by close contact and touch. Also, whether you're going to give someone COVID or not, it's filthy to use the bathroom and then refuse to wash.
Nonetheless, the pandemic has accumulated evidence that coronavirus transmission via fomites—that is, inanimate contaminated items or surfaces—plays a significantly smaller role, and airborne transmission plays a much bigger part, than previously anticipated. Linsey Marr, an environmental engineer and aerosols expert at Virginia Tech, told me that the same is likely true for other respiratory diseases such as influenza and coronaviruses that cause the common cold.
This realization isn't entirely new: Researchers at the University of Wisconsin discovered in 1987 that a group of men playing poker with "soggy," rhinovirus-contaminated cards were not infected, although another group playing with other ill players was. We've long believed otherwise since our understanding is based on flawed assumptions. The investigations that pointed to fomite-centric models of transmission were mostly virus-survival experiments, which evaluate how long a virus can stay on a surface. Many of them utilized excessively huge doses of virus or merely evaluated the existence of the virus's genetic material rather than whether it remained infectious.
For the time being, it is critical to avoid thinking in terms of black and white. All modes of transmission are possible, including spores, airborne droplets, and smaller aerosol particles. And the proportional breakdown will differ depending on the setting, according to Seema Lakdawa, an Emory University flu-transmission expert. Fomite transmission may be negligible in a grocery store, but it is not negligible in a day care, where children are constantly touching, sneezing on, and sticking things in their mouths. This idea has a corollary in that certain infection-prevention strategies work well in one context but not in another: It makes sense to disinfect a table in a preschool classroom on a regular basis; it makes less sense to disinfect the desk in your own private cubicle.
Much of the conspicuous cleaning we did early in the pandemic was unnecessary, according to Popescu, but she is concerned that we may have overcorrected by lumping some useful behaviors—targeted disinfection, even hand-washing in some cases—into the category of hygiene theater. Whatever the context, the experts I spoke with all agreed that these behaviors are still necessary when dealing with non-respiratory pathogens. Marr recently disinfected a number of high-touch surfaces around the house after several members of her family became ill with norovirus, an extremely unpleasant stomach bug that causes vomiting, diarrhea, and stomach cramping. Consider this: one of the country's foremost authorities on airborne transmission cleaning doorknobs and light switches.
With respiratory-virus season approaching, CDC Director Rochelle Walensky tweeted three pieces of health advice on Friday: "Get your annual flu vaccine and an updated COVID-19 vaccine." "Stay at home if you're sick," and don't forget to "practice good hand hygiene." She said nothing about masks or ventilation.
