The Centers for Disease Control and Prevention is warning what the future might hold in the United States when it comes to COVID-19, the disease caused by the new coronavirus. The agency said it expects to see the disease spread in the U.S., and it's not so much a question of if, but when. So far, there's been only one confirmed case here in Massachusetts. Dr. David Hooper, head of Massachusetts General Hospital's Infection Control Unit, met with WGBH News' All Things Considered anchor Arun Rath at Mass. General and gave him an update on where things stand. This transcript has been edited for clarity.
Arun Rath: The last time we spoke, we didn't know much about this virus. It now has a name, or at least the disease has a name: COVID-19.
David Hooper: That's right. And they, I believe, have now officially named the virus SARS-CoV-2, because it is genetically related to the SARS virus, although obviously has some distinct features.
Rath: Do we know more in terms of the incubation period for this virus and how it spreads?
Hooper: The incubation period still seems to be in the two to 14 day window. Most of the studies that have been published thus far show that the average is about four to six days for the incubation period before symptoms begin. How it spreads? It's clear that person to person spread occurs and certainly in family settings. There are data that also suggests that in some cases there may be opportunities for a person without symptoms to spread the virus to other people. We don't know the extent to which that occurs, but it's something that occurs already with influenza viruses that we see. But it makes it more difficult to control if you can't always rely on symptoms to necessarily indicate that someone might be having the virus in their body.
Rath: We've seen some countries imposing travel restrictions and shutting down certain parts of the country. Is that the right approach, is that how most countries would deal with it?
Hooper: Well, it depends, of course, on the particulars of the situation. Certainly if there is a substantial outbreak in an area, you would like to limit the opportunities for spread of infected persons to other areas.
Rath: In terms of travel restrictions internationally, at what point would it make sense for the U.S. to get concerned, for example to discourage or not allow flights from an affected country like Iran or Italy?
Hooper: We rely on the CDC and the State Department to set those levels of warning and they've been in place for travel to China. Just in the past 24 hours, the CDC recommendation is a level three now for travel to South Korea, where there is the largest number of cases outside of China. It's possible that there will be other changes in these alerts that might involve other countries like Italy. But South Korea is the only one that the CDC has made that recommendation on, in addition to China, thus far.
Rath: Since we last spoke about this, there have been many more deaths. The vast majority of them have been in China. Do we have a better sense of the mortality rate?
Hooper: There are larger numbers of cases and case series that have now been reported. The numbers or the proportion of illness in these different studies is affected by the sort of population that you studied. If you're only studying people that are showing up in a hospital, they are likely sicker than if you were studying a larger group of people who had milder flu-like illness. And so the range of data from these types of studies is that the mortality rate probably averages out around 2-percent. But in some of the largest studies, it's maybe even a bit lower than that, in the 1.4-percent range.
Rath: In terms of the scale, it doesn't sound like people should be too concerned about catching this virus locally?
Hooper: At this point in the United States, clearly, the risk of respiratory illness is much higher from seasonal influenza, which we're still in the middle of the flu season. It may have peaked, but there's still substantial flu activity out there in the Boston area. And so the risk of being exposed to the flu or catching the flu is hugely higher than the novel coronavirus at this point.
