TGC Professor Discusses Coronavirus Risks, Transmission Rates

Author: Jonny Lupsha, News Writer
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 Standford EdTech (Author)
EdTech Café is a podcast series produced by the educational technology team at Stanford Medicine.

By Jonny Lupsha, News Writer

The new coronavirus strain has killed more people in China than SARS did, The New York Times reported Tuesday. On the verge of becoming a global pandemic, the Wuhan coronavirus now infects 2,000 new people every day. A professor from The Great Courses helped us make sense of the respiratory illness.

Close up focused image of a blood sample tube with Coronavirus
According to the Centers for Disease Control and Prevention’s website, coronaviruses are named for the crown-like spikes on their surface. Photo by Soni’s / Shutterstock

According to the Times article, the new strain of coronavirus has killed 425 people as of Tuesday morning, which is more than the number of Chinese killed by the SARS outbreak in 2002 and 2003. “Some deaths still go unreported, and many residents in Wuhan, the epicenter of the outbreak in central Hubei Province, say they believe the true number of deaths across China may be higher than the official tally, because many of the ill have been turned away by overstretched hospitals,” the article said.

Dr. Barry C. Fox, Clinical Professor of Medicine at University of Wisconsin Medical School, taught The Great Courses lecture series An Introduction to Infectious Diseases. We spoke with him to understand important factors of the new illness, including risks, rates and methods of transmission, safety precautions, and comparisons to other recent pandemics.

Putting the New Coronavirus into Perspective

According to the Centers for Disease Control and Prevention (CDC), the new disease’s full designate is 2019 Novel Coronavirus, or 2019-nCoV. While many people refer to it simply as “coronavirus,” it isn’t the first of its kind.

“This coronavirus is most comparable with the SARS outbreak in 2003 and then the MERS outbreak,” Dr. Fox said. “All three of these are coronaviruses. There are now seven known coronaviruses; the first four were just thought to be benign viruses that caused cold-like symptoms and didn’t really come on the radar screen until 2003 when SARS came on the scene and was found to be a coronavirus.”

The CDC website explains that coronaviruses “are named for the crown-like spikes on their surface.” Knowing that SARS was a coronavirus helps lend perspective to 2019-nCoV.

“The outbreak now is probably more similar to what happened in the SARS outbreak—that is, that it originated in a place in remote China, likely due to animals and merchants in [a] market where there’s mixing of people and mixing of animals for food,” Dr. Fox said. “What’s slightly biologically different between the coronaviruses and the influenza virus that caused swine flu is that influenza viruses are often transmitted before people are symptomatic; the coronaviruses are usually, with rare exceptions, transmitted only when people are symptomatic.”

Understanding Transmission Rates

On the subject of transmission rates, the CDC explains that the rate at which a disease is transmitted is called its basic reproduction number, often written as R0 and pronounced “R naught.” “The basic reproduction number is an epidemiologic metric used to describe the contagiousness or transmissibility of infectious agents,” the CDC website said. Dr. Fox put 2019-nCoV’s R0 into perspective, as well.

“For every one case of the coronavirus, the current R0 is thought to be 2.6, so for every one case, it’s likely that the spread will be to 2.6 other people barring any other containment issues,” he said. “That itself is alarming, but it’s not particularly alarming because [with] something like measles, for example, the R0 is about 16.”

Dr. Fox said that one of the factors that affects transmissibility is whether the disease is symptomatic or not. People who have symptoms and feel sick are more likely to stay home to recover, which keeps them away from others and will lower the R0. On the other hand, if a disease is contagious and asymptomatic, it can spread more when one infected person feels fine but is out in the general public.

How We Fight Outbreaks

The SARS outbreak, Dr. Fox said, was stopped because people showed symptoms and were effectively quarantined, which broke the chain of transmission. “The MERS virus is slightly more sporadic and slightly more complicated.”

In other instances, new antivirals have proven effective.

“We talk about how desperate times call for desperate measures, and therefore there’s going to be trialing of things that are going to be outside the regulatory type of things that would happen in the United States or a worldwide basis to try to find something that’s maybe a ‘magic bullet’ for the disease process itself,” Dr. Fox said. “During the Ebola outbreak we had these transfusion and monoclonal antibodies that were being administered and we [didn’t] really know whether they were efficacious or not, but subsequently we know that they are, and they were approved for Ebola.”

Dr. Fox said that the standard answer from administrators in the medical world is that a vaccine for a new illness is a year away due to research, development, and safety testing. However, occasionally some of the work is already done, which may help solve the 2019-nCoV outbreak.

“They were working on—and they actually worked quite a bit on—a SARS vaccine because they didn’t know whether or not the SARS outbreak was going to be contained,” Dr. Fox said. “People are picking up on the research that was done on SARS and MERS vaccines and it’s their hope they may actually be able to substitute some important genetic sequences into the vaccine manufacturing process and speed the whole timeline up.”

Risks and Safety Precautions in the U.S.

Despite the high number of cases of 2019-nCoV reported throughout China, the risks in the United States are very low.

“The United States is taking some reasonable precautions in that the citizens that were evacuated from the Wuhan area are under observation and quarantine for 14 days,” Dr. Fox said. “It does not appear to be airborne, so if you’re in Dulles Airport and someone on the other side of the airport has coronavirus, you’re not going to get the coronavirus because it can’t really travel that far. Close personal contact within six feet is the most likely means of spread, so being in a place where there might be someone at risk is not likely to cause a transmission.”

However, Dr. Fox said, education is a good tool and the public should be commended for taking an interest in the disease process and for acquiring a basic knowledge of health care and the transmissibility of infectious disease. This can help with future illness prevention as well.

“I think influenza’s the most important thing going on in the US right now,” he said. “It’s so relatively easy to get a flu vaccine—it’s not a perfect system, but if you’re young and healthy and get a flu vaccine, you have a high percentage that that’s going to prevent you from getting the flu. If you do get the flu, you’ll have a very mild case of the flu.

Dr. Fox also stressed that the argument as to why people shouldn’t get a flu vaccine is a matter of disinformation. As far as the public is concerned, the focus has been less on coronavirus and more on the much higher rate of flu cases and flu deaths.

“So at least do your minimum responsibility and get a flu shot,” he said.

Dr. Fox’s course An Introduction to Infectious Diseases is available now.

Image of Professor Barry Fox, M.D.

Dr. Barry C. Fox is Clinical Professor of Medicine at University of Wisconsin Medical School. He received his undergraduate degree in Molecular Biophysics and Biochemistry from Yale University and his medical degree from Vanderbilt University.

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TGC Professor Discusses Coronavirus Risks, Transmission Rates
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