Updated: Jan 24, 2021
When the pandemic began, we knew very little about the SARS-CoV-2 virus. But disinfecting surfaces was something we could all do, so we employed Purell, soap & water, Lysol and Clorox wipes anywhere, everywhere and at any time. By mid-March, our nightly routine was a call to arms. “Fomites!” I cried as I swiped over countertops, door knobs, and any other surface within sight. Whatever we could do to decontaminate, we did. Disinfecting fomites, objects or surfaces that become contaminated with an infectious microbe, then are touched by a hand, and then transferred to a mucous membrane (eye, nose, or mouth), became a routine to decrease possible disease transmission.
My teenage son rolled his eyes every night before bed as I yelled “Fomites!” and waved Clorox wipes cheerily in his direction. I used a single precious wipe to work my way through a wipe-down routine as he sought refuge in his room. Wipe. Wipe. Cabinet pulls, door handles, toilet handles, remote controls, light switches, smartphones, and even thermostat buttons - nothing was ignored. About nine weeks in, or approximately 63 precious Clorox wipes later, I stopped.
I stopped because I am empirical. And empirically (much to my mortified son’s relief) there was no reason to continue. But hadn’t scientists determined that the virus could persist on surfaces for hours, even days? Indeed, they had. So why stop? Because new data indicated that while that evidence was not wrong, it was also likely not especially relevant. Those alarming early studies were based on experiments run in labs not in hospitals or the community where COVID-19 was spreading. While lab studies--which typically use high quantities of virus--do indeed indicate long survival on surfaces, these quantities are not necessarily generalizable to other settings.
The large amount of virus samples used and persisting in these studies far exceeds any measured in real life settings, including hospitals treating COVID-19 patients. It’s not surprising that the high-volume samples persisted on fomites for hours and days. Extreme exposures can lead to extreme outcomes that may not occur at different doses in different settings. It’s not unlike the lab studies of saccharin in the 1970s that showed large amounts of saccharin caused bladder cancer in rats. Over time, it became clear that these studies did not apply to humans, who consumed much smaller quantities of saccharin. In the SARS-CoV-2 studies, the high virus doses used to study surface transmutability within a laboratory setting, determined that the virus was detectable in a great volume, for a long time. Those early studies motivated aggressive measures to reduce fomite transmission but were based in extreme scenarios. However, at the time this was some of the only data we had.
But now science has filled in many of the gaps with several more recent studies questioning fomites as a meaningful source of disease transmission. On May 22nd, the CDC stated that fomite transmission “may be possible” but is not common. The World Health Organization noted on July 9, 2020 that there have been no disease reports that could be traced directly to fomite transmission.
Yet despite data supporting a low risk of surface-to-hand-to-face transmission, infection controls focus largely on preventing fomite transmission. Learned habits, especially ones that make us feel safe and in control, are hard to break. In those early months with limited disease information we used the disinfecting weapons we had at our disposal and launched a fomite-focused fight against COVID-19. We swapped our hand shakes for elbow bumps, our winter gloves for latex and found ways to reduce the everyday touches in our lives. Mail and groceries were quarantined for hours or days. In Seattle, we began to forego signing for the pizza, paying the bus fare, and my favorite: feeding the parking meter. May COVID-inspired free parking be an enduring pandemic legacy!
Our war on fomites may be ingrained after months of fear and it will undoubtedly help us prevent a host of other non-COVID infections such as norovirus, salmonella, and the common cold. However, it may make us more vulnerable to COVID-19 by drawing unnecessary attention to low-risk pathways while neglecting the higher impact aspects of infection control like ventilation, air filtration, and air disinfection. In our effort to reduce fomite risk, we may neglect higher impact infection risks.
My bank is like this with it’s new, abridged COVID hours that close the bank early for disinfection each day. The flipside, of course, is that the banking is seeing more customers in less time and increasing the number of people at the bank at one time. And yet the role of larger group sizes and greater density are known and established risk factors for transmission. At the post office, I see staff wearing gloves, yet not propping open the lobby entry door even on a very temperate day. Precautions against fomite transmission are ubiquitous yet attention to crowding, HVAC systems, ventilation, and air purification are not. Quarantining objects and intense disinfection protocols represent time, money, and energy spent on actions unlikely to offer substantial return in the form of COVID-19 transmission reduction.
Too much focus on surface hygiene at the expense of other risk reduction efforts is an unfavorable tradeoff. Recently, a client asked me about hiring for positions to wipe down objects and surfaces after each touch. She was considering a plan to hire multiple full-time workers - one in each department. While it’s a great plan for getting people back-to-work in a soft economy, it’s much less helpful for infection control. This client, like all of us, had finite resources and had spent none on understanding indoor airflow, updating HVAC systems, or on air disinfection. Our current COVID-19 “back to work” protocols focus too much on surfaces and not enough on the air.
The SARS-CoV-2 virus is transmissible through the air. And infectious people spread the virus by exhaling it through coughing, singing, speaking, or even breathing. Sometimes the virus is in the form of heavy, wet droplets that fall to the ground quickly near the infectious person; yet it is also likely that some droplets are smaller, lighter and float in the air for extended time and distances. Whether in the air for seconds or minutes, the virus is continually released as the infected person coughs, speaks, or exhales. Over time and without proper air exchange and disinfection, the virus builds up in the air, reaching the threshold for a minimal infective dose when inhaled.
How can we reduce transmission risk in this context? What is the merit of disinfecting the air, increasing its volume, exchanging it regularly, and documenting air flow patterns? It's high and well worth considering how it can reduce transmission risk. Some excellent tips on this can be found here. In the meantime, stay safe and keep an eye out for November's blog: "Thanksgiving Dinner And Other Conundrums: A Pandemic Playbook For Holiday Celebrations"