COVID-19 still has a lot of unknowns—but here's what we know about how the virus is transmitted.

By Jessica Migala
Updated March 24, 2020

With more than 46,000 confirmed cases of coronavirus in the US (and more than 392,000 cases worldwide), it's clear that the novel coronavirus (aka COVID-19), along with the anxiety surrounding it, isn't going anywhere soon.

Because the virus is so new (it's technically called SARS-CoV-2, FYI), lots of the fear surrounding COVID-19 stems from how little we know about it. Luckily, experts do know some pretty important things about the virus' transmission, or how the coronavirus does—and doesn't—spread.

In general, how does the coronavirus spread

According to the Centers for Disease Control and Prevention, COVID-19 is mainly spread from person-to-person, usually via close contact (within six feet). It can spread through physical contact like handshaking if someone's hands are contaminated with the virus. And it can also spread through respiratory droplets produced when an infected person coughs or sneezes (again, that's why the six-feet rule is handy: those droplets can travel that far, and land on another person's mouth or nose, and can even be inhaled).

The virus may also spread from person-to-person through surfaces that have been touched by those infected. "A sneezing or coughing person will cover their mouth, get it all over their hand, and then touch something that you then touch," Robert Murphy, MD, an infectious disease expert at Northwestern University, tells Health. The virus can then gain entry into your body when you touch your own face, he adds. That’s precisely why experts can only preach basic disease-prevention measures, like washing hands correctly (20 seconds with soap and water) and regularly, wiping down common surfaces, and staying away from sick people.

Lastly, another possible way coronavirus can spread between people is via fecal transmission. According to recent research from the Chinese Center for Disease Control and Prevention (CCDC), those with confirmed cases of the novel coronavirus (aka, COVID-19) have live virus in stool specimens, meaning there's a possible fecal-oral route for the virus, as well.

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Can you tell if someone is sick with coronavirus?

Unfortunately, the only way to truly know if someone has COVID-19 is to test them—that's because the symptoms of the illness look extremely similar to that of the common cold or flu: cough, fever, body aches. It's also important to know that not everyone who is infected with coronavirus shows symptoms—as is the case with asymptomatic carriers, according to The New York Times, or those who carry the virus around, spreading to other people, but never falling ill themselves.

Per the CDC, it's possible that some spread may occur before people infected with COVID-19 show symptoms, but it's probably not the main mode of transmission. It's currently believed that people are most contagious when they are most symptomatic.

How long does coronavirus stay on surfaces?

The recent coronavirus outbreak sparked a 2020 review published in the Journal of Hospital Infection, which looked at other coronaviruses (including SARS, MERS, and other endemic human coronaviruses), and determined that they can live on surfaces like metal, glass, or plastic for anywhere from two hours to nine days. Subsequent research in the New England Journal of Medicine found that the virus can live on copper for up to four hours, on cardboard for up to 24 hours, and on plastic and stainless steel for two to three days.

However, investigators examining outbreaks of COVID-19 on three cruise ship voyages in February and March reported the first evidence that the virus may hang around much longer than than initially thought. Traces of the virus were found in the cabins of infected Diamond Princess passengers (including symptomatic and asymptomatic individuals) 17 days after their cabins were vacated, according to the March 23 Morbidity and Mortality Weekly Report from the CDC. However, the authors of the report say the data cannot be used to determine whether the virus from transmitted from person to person through contaminated surfaces.

Even if we don't know exactly how long the virus lingers on surfaces, we do know that disinfecting surfaces is considered "best practice" for helping to prevent transmission of the virus. So again, wiping down common surfaces (and avoiding touching common surfaces if possible) will help decrease the spread. The CDC recommends cleaning tables, countertops, light switches, doorknobs, and cabinet handles regularly. However, it’s unlikely that COVID-19 is spread by mail or packages; if it were, there’d be even more cases, says Dr. Murphy.

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Does coronavirus spread through food?

It's a fair question—especially since lots of other viruses, like norovirus or other gastrointestinal viruses can spread via contaminated food. But, while a risk can't be ruled out if an infected person prepares the food, or you buy it from a highly trafficked buffet, the coronavirus doesn't appear to be spread by food, per The New York Times.

The main way respiratory illnesses are spread is by touching a common surface a sick person touched and then putting your hand up to your eyes, nose, or mouth, says Dr. Murphy.

What exactly is "community spread," and how is that related to coronavirus?

This term—"community spread"—has come up recently in news reports, specifically ones focusing on a small number of cases in California, Oregon, and Washington, according to STAT News. Essentially, according to the CDC, community spread occurs when a person within a specific community is diagnosed with an infectious illness, like COVID-19, that isn't linked to travel history or another known case of the illness.

Community spread is now being detected in a growing number of countries and in some areas of the US, says the CDC, which only solidifies the need for people to follow the CDC's preventive measures: avoiding close contact with people who are sick; avoiding touching your eyes, nose, and mouth; staying home when you're sick; frequently disinfecting objects that are touched regularly; and washing your hands often with soap and water, especially before eating and after going to the bathroom.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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