• George Wang, MD, PhD

Does the novel coronavirus survive in the air and on surfaces?

What can we do to help stop the spread of COVID-19?


Most of us are now familiar with the critical step in preventing the person-to-person spread of the coronavirus that causes COVID-19 (coronavirus disease 2019): social distancing and social isolation. The reason why social distancing or isolation is important is that the novel coronavirus is thought to be spread primarily through respiratory droplets, the same way that the influenza virus does. This means that the virus is released in respiratory secretions when an infected person coughs, sneezes, or talks, and if those respiratory droplets makes a direct contact with another person’s mucous membranes on the eyes and in the nose and mouth, the virus is transmitted. Or, if a person touches an infected surface (where virus-containing droplets landed) and then touches their eyes, nose, or mouth, the virus can be transmitted as well.


Because respiratory droplets usually do not travel more than six feet (about two meters), the caution of socially distancing ourselves from others at least six feet apart is well founded.


However, what about the very small respiratory droplets (aerosols) that may be released into the air and potentially travel farther than six feet or linger in the air?


An experimental model of human cough showed that when we cough, we can potentially produce droplets ranging from 0.1 - 900 microns in size (1). (One micron is one-millionth of a meter, or 1/25,400th of an inch.) Droplets 5 microns or larger are traditionally thought to not travel more than six feet, but droplets smaller than 5 microns (aerosols) can remain suspended in the air for extended periods. What's more, an experimental model that takes into account the fluid mechanics of the forceful ejection of respiratory droplets during coughs or sneezes suggests that even the larger 5 micron droplets can travel up to 8 meters (26 feet) (2).


Researchers recently found that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, remains viable in aerosols for 3 hours, though it is unknown how much longer it remains viable beyond 3 hours (3).


The WHO and CDC guidelines for the control of COVID-19 infection in the hospital and other health care settings call for droplet precautions. Airborne precautions, a higher level up in stringency, are recommended only if an aerosol-generating procedure will be performed.


The same researchers in the above study also tested the duration of viability of SARS-CoV-2 on different surfaces: plastic, stainless steel, copper, and cardboard. They found that the virus survived longer on plastic and stainless steel surfaces than on copper and cardboard (3). On cardboard, no viable virus was detected after 24 hours, and on copper, no viable virus was detected after 4 hours. However, the virus survived on plastic and stainless steel surfaces up to 3 days. (The median half-life of SARS-CoV-2 on stainless steel was 5.6 hours and on plastic was 6.8 hours.)


What does this all mean for us when it comes to mitigating and preventing COVID-19? This research suggests that, theoretically, it is possible for the virus, SARS-CoV-2, to be transmitted through aerosols that carry viable viruses for at least 3 hours from the time they were released from an infected person. However, we do not currently have the clinical data to better understand how much (what dose) of such infected aerosols are necessary to actually cause an infection in the person who may come in contact with such aerosols.


As with all viral respiratory infections, another crucial variable that determines whether a person can become infected is the health of that person. The immunity of the person (how healthy and strong the immune system is) and the physiologic reserve of the person can determine whether or not the person actually gets sick from the virus, and how sick they may get. The physiologic reserve refers to, for example, how well the person can contain the virus in the airways and mobilize their body’s healing capacity, which can involve the circulatory system, respiratory system, immune system, and essentially all other organ systems and tissues in the body.


This is why it is so important to follow healthful dietary and lifestyle choices, so that we are optimizing our physiologic reserve and immune function ("improving the terrain"), so that we can improve our chances of overcoming future challenges. Social distancing and social isolation can also reduce the chances of coming into contact with infected aerosols that may linger in enclosed spaces, though, again, it is unclear how much impact such aerosols can have on causing COVID-19, or whether such aerosols can cause COVID-19.


Right now, however, as global citizens, what we can do is to abide by the guideline of social distancing and social isolation. This is the least we can do on our part to help protect people who may be more likely to be infected by the virus and to become critically ill from the virus, and at the same time protect ourselves and our families as well.


Of course, we ultimately cannot foresee which ones among us will be afflicted by COVID-19, but as I have seen in practicing integrative medicine and functional medicine, every little thing counts. This vague statement--"every little thing counts"--may be difficult to test in a scientific experiment, but mindful and experienced clinicians will know this to be true.


Each little thing may seem non-decisive—such as being watchful of potentially infected surfaces; washing hands; eating abundant whole, organic plant foods that nourish us with vitamins, minerals, and phytonutrients that improve our physiologic reserve and immune system; minimizing or eliminating processed foods or animal foods that may be detrimental to health; being physically active; practicing mindfulness; being considerate of one another; caring for one another; and being prudently open minded. But when added together, these small choices and actions can make the difference in whether we triumph over the health and social impacts of this global catastrophe.


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Information on COVID-19 continues to change frequently. The information discussed here is only current as of the date of the blog. The WHO and CDC provide updated information on COVID-19:

https://www.who.int/health-topics/coronavirus

https://www.coronavirus.gov



References

1. Zayas, et al. 2012. Cough aerosol in healthy participants: fundamental knowledge to optimize droplet-spread infectious respiratory disease management. BMC Pulm Med, 12, 11.


2. Khamsi, R. 2019. They say coronavirus isn't airborne—but it's definitely borne by air. Wired [Online]. Available: https://www.wired.com/story/they-say-coronavirus-isnt-airborne-but-its-definitely-borne-by-air/ [Accessed March 20, 2020].


3. Van Doremalen, N., et al. 2020. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med.



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