Updated: Apr 20, 2020
With COVID-19 introducing unprecedented changes to all of our daily lives, we’re questioning activities that were previously second nature. Thus far, we’ve been inundated with messaging to practice social distancing, to reduce contact to our eyes, mouth and nose, and to regularly wash our hands.
But what about when we go grocery shopping or get food/packages delivered to our homes?
The other day my mom practically hosed down a family-sized box of Honey Bunches of Oats with disinfectant spray after a Costco run- was that just extra, or actually effective?
The dynamic nature of the outbreak poses challenges to its containment since the information we’re receiving is evolving continually—so in the meantime, let’s stick with what we know.
Unlike gastrointestinal viruses (e.g. Norovirus) which are food-borne, there is currently no evidence that food or food packaging is associated with transmission of the novel coronavirus. Transmission of the novel coronavirus is primarily thought to spread via human transmission as a result of close contact or exposure to respiratory droplets. While those droplets can survive on surfaces for extended periods of time, this is not thought to be a primary method of transmission.
The New England Journal of Medicine recently published a study that compared the aerosol and surface stability of SARS-CoV-2 to SARS-CoV-1 in five environmental conditions: aerosols, plastic, stainless steel, copper and cardboard. SARS-CoV-1, identified in 2003, is the most closely related human coronavirus to the strain currently responsible for the COVID-19 pandemic. Figure 1A from the study, included below, depicts the reduction in virus titer over time. On cardboard and copper surfaces no viable SARS-CoV-2 was measured after 24 hours and 4 hours, respectively. This was compared to SARS-CoV-1 where no viable virus was measured on cardboard and copper surfaces after 8 hours on either type of surface. Viral viability on surfaces composed of stainless steel or plastic was observed to be longer; however, the surface viability was comparable between the two strains. On stainless steel, the virus titer was reduced by a factor of 1000 over the course of 48 hours, and 72 hours on plastic surfaces.
Ultimately since the surface stability of the two strains, SARS-CoV-1 and SARS-CoV-2, was found to be similar, the authors propose alternate factors that might contribute to the difference in epidemiological characteristics of the 2002 SARS epidemic and the current COVID-19 pandemic. High viral loads of SARS-CoV-2 in infected individuals or the potential for asymptomatic transmission, for instance, are possible contributing factors to the distinction between the previous SARS and current COVID-19 outbreak, both of which point to human-to-human transmission as one of the primary methods of exposure.
Viability of SARS-CoV-1 and SARS-CoV-2 in Aerosols and on Various Surfaces
Source: N van Doremalen et al. N Engl J Med 2020. DOI: 10.1056/NEJMc2004973
All that said, did we need to disinfect that box of Honey Bunches of Oats? For peace of mind, I'd give cardboard boxes, plastic containers or metal food containers a quick wipe-down, especially if you're in an area impacted heavily by the outbreak. But the real culprits are likely shopping carts or electronic card machines in stores. So, best practices thus far include keeping all food contact surfaces sanitized, researching which grocery stores in your area are regularly sanitizing their stores, and practicing social distancing whilst grocery shopping. So, instead of soaking your groceries or packages in disinfectant, wash your hands thoroughly after you’ve come home, and disinfect your countertops and utensils prior to eating.
For some more clarity on this topic, check out Dr. Anthony Fauci’s interview on The Daily Show with Trevor Noah here (1:50-4:30). And check out Dr. Sanjay Gupta's video on how to sanitize groceries here.
B.A. Neurobiology & French | UC Berkeley
MPH Candidate | Dartmouth College
Monica Ngyuen, Minda Liu, Arushi Krishnan, Divya Chawla
MPH Candidates | Dartmouth College
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1. Food Safety and the Coronavirus Disease 2019 (COVID-19). U.S. Food and Drug Administration.https://www.fda.gov/food/food-safety-during-emergencies/food-safety-and-coronavirus-disease-2019-covid-19. Updated March 26, 2020. Accessed March 23, 2020. 2. How Coronavirus Spreads. Coronavirus Disease 2019 (COVID-19).https://www.cdc.gov/coronavirus/2019-ncov/prepare/transmission.html. Updated March 4, 2020. Accessed March 23, 2020. 3. N van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. 2020.