Coronavirus Outbreak: 5 Questions?>
Expert Q&A

Coronavirus Outbreak: 5 Questions

by David Tuller, DrPH  

Since Chinese authorities disclosed in December that a previously unknown coronavirus was causing a wave of respiratory infections, the illness has spread rapidly. As of Feb. 13, 2020, more than 44,000 cases have been identified in China as well as hundreds of cases in more than 20 other countries, including 15 cases in the United States. More than 1,000 people have died (all but two in mainland China). The pathogen is in the coronavirus category, which also includes the virus that causes the common cold. This family of viruses was also responsible for the SARS epidemic in 2003 and the MERS outbreak in 2013.

Beginning the last week of January, major airlines announced they were curtailing flights to and from China. The U.S. and other countries have also begun quarantining travelers returning from Hubei Province, China, where the new virus was first detected (in the city of Wuhan). They will be observed for 14 days (the incubation period) to see whether they develop symptoms of infection. We spoke in early February with Arthur Reingold, MD, an infectious disease expert and the head of the division of epidemiology and biostatistics at the UC Berkeley School of Public Health, about the most recent developments as well as what is and isn’t known about the new virus.

BW: What is the latest on the coronavirus?

AR: There now appears to have been transmission of the virus outside of China. In at least one case, in Germany, transmissions seems to have occurred from someone who was asymptomatic at the time. We don’t know yet how common that sort of transmission is, but that has changed people’s thinking. Certainly that and other factors have led to more robust measures in an effort to stem the spread.

So first, there are lots more travel restrictions in place in terms of halting flights going to and from China. However effective that will or won’t be, that clearly is a decision that’s been taken by airlines and a number of countries. Second, a decision has been made in a number of countries, including the U.S., that when people return from China, and Wuhan in particular, they’re going to be quarantined for 14 days. So that’s happening now at a military facility in southern California, and my understanding is that the plan is for other parts of the country to do the same.

Do you think the efforts to slow the spread will be successful?

Health authorities in the U.S. and other countries are clearly attempting to maximize caution and minimize the chances that there will be transmission locally. It really is a substantial effort in this case. In southern California, they’re on a military base that has the rooms to house people, the kitchens for preparing food, etc. We don’t really have civilian quarantine facilities in the U.S.

To quarantine one person is one thing, but to do it for hundreds of people getting off an airplane creates a whole other set of logistical issues. Once you do it on this scale, you need substantial resources. Because there is so much uncertainty about transmission, I understand why it’s being done and why authorities have decided to go in this direction.

Do we know much about how this is transmitted?

We’re still learning a lot about the virus. For many respiratory infections, figuring out how much is via aerosolized particles and how much from droplets that require being within a few feet of someone is difficult. If you have an animal model you can study it, but that’s not the case here. For some bugs, airborne transmission is probably not a factor at all and they’re only spread through droplets. It’s not so easy to figure that out in the real world.

Should people in the U.S. worry about being exposed?

The average person walking down the street in California or Indiana or New York is at very small risk of coming into contact with this novel coronavirus. At this point, if people are worried about their health, they should get a flu shot, they should stay home if they’re sick, cover their mouth or nose if they cough or sneeze around other people, and wash their hands regularly. But am I changing my behavior on a day-to-day basis, am I wearing a mask? No.

I also think making decisions about social distancing measures based on race or ethnicity is deeply problematic. We’ve got large numbers of Asian Americans in the Bay Area who have got no more likelihood than anyone else of being exposed.

You mentioned that people thinking about their health should get flu shots. Do people tend to focus on the unknown dangers more than known dangers?

Well, we know a lot about the flu but we know very little about this novel agent. And we have a flu vaccine, however imperfect it is. We don’t have a vaccine for this virus, and no matter how fast people are working, we’re not going to have a vaccine to deploy against this realistically for six to twelve months. So hopefully the outbreak is going to be over long before any vaccine is available.

This is a good example of how familiarity breeds contempt. People think they know about flu, they may minimize its importance, they basically don’t attach a lot of significance to it. Whereas this is new, it’s unknown, and it’s scary. Whether the risks are greater or lesser is at this point less of an issue than perception and anxiety and lack of information.

For ongoing updates and recommendations as the situation develops, visit the CDC's 2019 Novel Coronavirus web page or the World Health Organization website.

This opinion does not necessarily reflect the views of the UC Berkeley School of Public Health or of the Editorial Board at

First published February 4, 2020; updated February 13, 2020.