Coronavirus: What We Know

The following interview was conducted by Michelle Samuels (SPH)

A new coronavirus that originated in the city of Wuhan, China, at the end of 2019 has now sickened thousands of people and killed more than 100, with cases confirmed in many countries around the world—including five confirmed cases in the US and one possible case in Canada.

SPH discussed the outbreak with two faculty members who are experts in infectious disease. Davidson Hamer is a professor of infectious diseases (BUSM) and global health (SPH). Jean van Seventer is a clinical associate professor of environmental health (SPH), with a focus on animal-to-human infectious disease transmission.

They co-teach PH 825, a core course in emerging infectious diseases at SPH that will definitely be adding this new virus to the curriculum.

SPH: What is the new coronavirus?

van Seventer: 2019-nCoV (2019 novel coronavirus) belongs, as its name indicates, to the large family of coronaviruses. There are seven coronaviruses that can infect people, including some that are agents of the common cold, as well as severe acute respiratory syndrome (SARS-CoV) and Middle East respiratory syndrome (MERS-CoV). All are thought to have originated in animals.

Where did it come from?

van Seventer: The genetic sequence of 2019-nCoV is very similar to SARS-CoV, suggesting that it too originated in bats. Similarly, the linkage of many early cases to a large market in Wuhan suggests possible spillover to humans from one or more market animals, or animals infesting the market. Thus far, however, while environmental samples from the market have tested positive for the virus, animal samples have not. We do not know whether 2019-nCoV entered the human population directly from bats, or from bats to another animal and then to humans, but the striking similarity in sequence between 2019-nCoV virus isolates from multiple patients suggests whatever the path of spillover from animal to humans, entry of the virus into the human population occurred very recently.

Hamer: It’s clear now that there’s person-to-person spread, and that seems to be mainly through respiration droplet—through people coughing and sneezing. But given what we learned about SARS, contact with other fluids including feces may turn out to be a potential mode of transmission of this virus as well. Like SARS, some patients are presenting with diarrhea, which may turn out to be full of contagion—we don’t know yet.

van Seventer: 2019-nCoV appears to enter cells using the same receptor as SARS, making it likely that it spreads from both the respiratory and gastrointestinal systems.

How serious is this outbreak? How worried should people around the world be?

Hamer: We still don’t know a lot about the severity of this disease. We can safely say that a proportion of patients have been ill enough to require hospitalization and intensive care support. We don’t know yet what the case-fatality is yet, but clearly some people are dying from it. We do know that a good proportion of those who have died were older—50 years old and above—and/or had other medical conditions that may have increased their risk. On the other hand, there’s some evidence that at least a subset of people who are dying were young and healthy.

van Seventer: People hear ‘pandemic’ and worry, but swine flu was a pandemic and it turned out to be similar to the severity of the annual flu. Headlines such as ‘600 More Cases’ can be somewhat misleading in conveying how quickly the virus is spreading.

As with the beginning of any epidemic, particularly when a new pathogen is involved, cases can go unrecognized because health professionals are not on the lookout for them. Then, as health officials become more aware of the problem and surveillance for cases is enhanced, there is an increase in case recognition, which is at least part of what we are seeing here.

How are governments and other authorities responding?

Hamer: I think China’s response has been remarkable. It’s been vigorous and intense ever since figuring out that there was an outbreak. It’s currently the Lunar New Year, and the government is actually extending the timing of the New Year celebration, saying, ‘Celebrate in February, not now!’ because this is a time when people are moving all over China. It’s terrible timing—or good timing, if you’re the virus—so I’ve been really impressed by China’s response.

van Seventer: The Chinese government’s response to SARS was, particularly in the beginning, extremely opaque and it really hindered efforts to prevent global spread of the disease. China took a lot of heat for its lack of transparency around SARS, and its response now appears to be much more proactive and transparent in its interactions with the global community.

Hamer: The WHO is also very involved, with the Director-General currently in Beijing. The WHO has not yet declared this a public health emergency of international concern (PHEIC), but then they recommended airport screening—which in the past they haven’t been big proponents of, because, honestly it’s not clear how well it really works.

The US and a lot of other countries are doing airport screenings for anyone coming in on a direct flight from China. The Centers for Disease Control and Prevention (CDC) has reopened its Emergency Operations Center for this new virus response. Lots of governments are really mobilizing, but the most important one is China.

Between trying to isolate populations, limit travel, and screen travelers, will all of these measures help prevent the spread of this disease? That’s an open question.

In Wuhan, when they shut down the city and said that people couldn’t go in or out of the city, five million people heard it was coming and left the city [of 11 million], so about half the population fled. That’s the challenge: You can’t really control human behavior.

What can people in the US do to protect themselves?

​Hamer: Healthcare workers in China are at high risk, as is anyone who’s traveled to China and any healthcare workers who have been exposed to someone who’s traveled to China.

Hospitals need to be ready and prepared to put people in respiratory isolation and have protocols in place to quickly act and respond. The big thing is, if you see a patient in an emergency room or primary care, you need to take a travel history. We learned that with Ebola, where a travel history wasn’t taken right away with a man who came back from Liberia to Dallas and exposed a bunch of healthcare workers, a few of whom became ill.

I would not recommend travel to any part of China right now, unless you’re a medical worker and you want to go help with the outbreak response.