COVID-19 Transmission: Surfaces

There is some risk of COVID-19 transmission from surfaces, but the primary disease transfer mode is airborne transmission. Several studies have analyzed the detection of COVID-19 on various surfaces. One such study, published by the New England Journal of Medicine in March 2020, largely shaped the discussion around SARS-COV-2 (the virus causing COVID-19 disease) transmissions via surfaces. This study concluded that the SARS-COV-2 virus could linger on surfaces for a varying amount of time.

Analyzing COVID-19 Surface Transmission

The study’s information is the basis for public health authorities recommending cleaning surfaces frequently; however, despite the data’s validity, this study and others have been criticized for not reflecting real-world scenarios. Some research tactics included an abnormally high viral load, highly controlled environments, or mRNA detection (the “corpse” of a virus.) None of these methods are comparable to real-life scenarios. A study published by the National Institutes of Health took samples from various locations in a hospital in Wuhan, China and tested for COVID-19 using PCR tests. Only 10 of 318 samples came back positive, leading the authors to conclude that surface transmission may not pose a significant risk to the spread of COVID-19. This study more accurately reflects real world conditions, but only took samples from one hospital.  To accurately assess surface transmission, more real-word studies are needed.

Harvard T.H. Chan School of Public Health’s Joseph Allen and other authors pointed out in an op-ed, “We don’t have a single documented case of COVID-19 transmission from surfaces. Not one.”  They explained that individuals could reduce the risk of fomite transmission from the SARS-COV-2 virus with regular handwashing or use of hand sanitizer. In addition, an Oxford University meta-analysis of 60 studies found no evidence that surfaces could cultivate COVID-19 viruses.

Leading national and international organizations have begun to de-emphasize the risk of transmission COVID-19 from surfaces:

• The Centers for Disease Control and Prevention (CDC) advises that although possible, “spread from touching surfaces is not thought to be a common way that COVID-19 spreads.”
• The European CDC, noting the pitfalls of the studies mentioned above, advises, “In practice, there is no evidence of COVID-19 transmission through contaminated packages.”
•  The National Academy of Scientists (NAS) acknowledges the presence of COVID-19 on surfaces (again noting the pitfalls of published studies) but calls for more research to find if this is enough to cause infection.
• The World Health Organization (WHO) maintains that “It is not necessary to disinfect food packaging materials, but individuals should wash their hands properly after handling food packages and before eating.”

Contracting COVID-19 from Surfaces is Unlikely

Dr. Anthony Fauci, the nation’s top infectious disease specialist, explained in August 2020, “It is conceivable but improbable that you could get it through fomites—meaning inanimate objects… doorknobs, or computers. It can occur, but it is [a] minor component of transmission.” Professor Linsey Marr, an engineering professor at Virginia Tech who studies airborne transmission of infectious disease, notes that three steps must occur to cause infection from COVID-19 transmission, reducing the likelihood:

1. There must be enough of the virus on the surface to cause infection
2. The virus must survive on the surface, and body
3. The virus needs an entry point- such as eyes or mouth

Therefore, individuals can effectively mitigate COVID-19 surface transmission by regularly washing their hands and avoid touching their faces.

WHO, China, and Frozen Foods Transmission

Authorities in China have claimed for months that several outbreaks of COVID-19 in their country can be traced back to imported frozen foods. Chinese authorities have placed strict regulations on frozen food imports, including increased surveillance of packaging plants and additional screenings. These policies have reduced the number of frozen food imports brought into the country. Last week, the WHO accidentally sent out an early draft with new advice, which stated COVID-19 could be introduced into a country by imported frozen food. WHO officials quickly responded that the draft was sent in error and the language was not finalized. They also stated that the draft included new scientific findings presented from China to the WHO, but that officials had not yet cleared the document for publishing.

China’s trade partners, including the US and EU, are disputing the findings surrounding frozen-food transmission, arguing that the false assessment is an effort to disrupt trade and promote the false narrative that the pandemic began outside China.

The Science Behind Frozen Food Transmission

Studies have shown that COVID-19 can survive in a frozen state for long periods, including a foods’ surface; however, the risk of contracting the virus from frozen food or packaging is low. Chinese authorities conducted PCR testing on 1.29 million samples and detected COVID-19 in 47 cases, with no evidence that the virus was viable. Additionally, Vincent Munster, a virus ecologist at the National Institute of Allergy and Infectious Diseases, contends that freezing reduces the amount of viable virus on a surface by approximately 90%. Individuals can reduce the risk of contracting COVID-19 from frozen food by washing their hands after touching packaging and cooking foods at high temperatures. Unfortunately, this is not possible for frozen foods like ice-cream. There appears to be some risk of COVID-19 spreading via frozen food, but the CDC maintains that this risk is very low.

Spread Through Respiratory Droplets Should Be The Priority

Health experts are emphasizing surface cleaning less than they did at the start of the pandemic. In fact, there is some risk that overuse of disinfectants can harm health. A study published by the National Collaborating Centre for Environmental Health (NCCEH), a Canadian thinktank, found that acute health effects such as asthma caused by overexposure to cleaning products increased in 2020, potentially due to increased cleaning habits during the pandemic. More recently, scientists have emphasized that risk mitigation efforts should focus on reducing transmission via air rather than COVID-19 surface transmission.

Harvard T.H. Chan School of Public Health’s Joseph Allen and other authors noted in an op-ed that: “If the vast majority of transmission occurs through the air rather than fomites, and airborne transmission is what is driving superspreading events, then we should shift our effort toward cleaning shared air, not shared surfaces.” Professor Marr, cited previously, stated, “Instead of paying so much attention to cleaning surfaces, we might be better off paying attention to cleaning the air, given the finite amount of time and resources.” Dr. Kevin Fennelly, a respiratory infection specialist with the National Institutes of Health (NIH), agrees that more enclosed businesses, like restaurants, should put more effort into improving ventilation.

Recommendations

Efforts to mitigate the spread of COVID-19 should focus on preventing the direct transmission of the virus- respiratory droplets. Health officials encourage social distancing, mask-wearing, and improving ventilation. Transmission from surfaces is not common, but businesses should continue to regularly clean high-touch objects such as doorknobs or shared scanners. Individuals can mitigate the risk of transmission on other surfaces, such as packages, with frequent hand washing/ sanitization.