Outbreak Experts: What to Expect Next from Coronavirus
Researchers from BU’s National Emerging Infectious Diseases Laboratories explain how the virus “jumped” from animals to humans and how lethal it might prove to be
The world has been on high alert since December 2019, when a highly contagious respiratory illness caused by a new coronavirus began to break out across China. It has since spread to more than a dozen other countries, infected more than an estimated 6,000 people, and killed at least 132 of those sickened. Meanwhile, infectious disease researchers and global health experts are racing to learn more about what species of animal the disease came from and how deadly it may prove to be in humans. All but 68 of the confirmed infections have taken place in mainland China, according to the World Health Organization.
The outbreak, believed to have originated in a live animal market in the Chinese city of Wuhan, will likely continue to spread. Although officials in China recently expanded a travel lockdown that impacts nearly 35 million of the country’s residents, the onset of the outbreak arrived just as travel spiked around celebrations for the Lunar New Year, which occurred on Saturday, January 25.
At this point, it does not appear to be exceptionally lethal.
Last week in the United States, the first case of coronavirus was confirmed in Seattle, Wash. Since then, four additional cases have been confirmed, two in California and one each in Arizona and Illinois. All of the infected individuals recently traveled from Wuhan, China. A number of international airports in the United States are screening travelers for symptoms of the illness, including Boston Logan International Airport. There has yet to be any confirmed cases in Massachusetts, but that isn’t stopping Boston University officials from keeping an extra close eye on the outbreak.
To learn more about the new coronavirus and what we can expect from the outbreak in the days ahead, The Brink spoke with Mohsan Saeed and John Connor from Boston University’s National Emerging Infectious Diseases Laboratories. Saeed studies emerging viruses that affect the respiratory system in humans, similar to the newly identified coronavirus. Connor researches what makes viruses so effective at infecting animals and humans and recently helped develop a diagnostic tool to differentiate fevers caused by the Ebola, Marburg, and Lassa viruses from ones caused by the malaria parasite.
The Brink: What do you know about this new virus so far?
Mohsan Saeed: We know the virus belongs to the Coronaviridae family, which is the same family that SARS and MERS belong to. Those two coronaviruses have caused significant outbreaks in the past two decades. This new coronavirus mainly affects the respiratory system, and the disease symptoms are similar to the ones caused by SARS, including a fever, cough, and difficulty breathing. Symptoms typically appear within five to six days of infection. However it’s possible that they may appear anywhere between 2 and 14 days from exposure. Since the virus seems to affect the lower respiratory system, it can potentially cause pneumonia or more severe disease in some patients, particularly those of higher age or in people with an existing disease condition.
The origin of the virus appears to stem from a live animal market in Wuhan, China. How does a virus like this spread from animals to humans?
John Connor: Viruses have to get into living cells in order to make copies of themselves. To do that, they have a protein that acts as a key to get into a cell, like a door lock. So, an animal virus has a protein key that will allow them into an animal cell. Often, a key that works on animal cells, like bat cells, won’t let that same virus enter into human cells. From time to time, however, there will be mutations or other types of changes to the protein key of a virus that turn it into a master key, able to open the doors of both animal cells and human cells. When this happens, a virus can now “jump” from animals to humans, a process called zoonotic transfer. The new coronavirus, similar to SARS, appears to be another example of a virus that successfully made the jump.
What factors increase the risk of zoonotic transfer?
Connor: Current evidence suggests that being close to different animal species increases the risk. For many years, human coronavirus infections were associated with mild diseases. But the SARS outbreak at the beginning of the millennium was associated with the jump of a coronavirus from animals to humans, and it caused severe respiratory illness in humans.
Why does zoonotic transfer pose such a threat to humans?
Connor: Generally, these jumps bring something new into the human disease arena, which is the most dangerous aspect of zoonotic transfer. That’s in contrast to a virus like influenza, which we already have good diagnostic tests for, are familiar with how it’s transmitted, and know how to minimize transmission—therefore we have a large capacity to respond to flu outbreaks in various ways. For the new coronavirus, all of the tools we need to effectively find and fight the disease are either just being rolled out or don’t exist yet, a concerning aspect of trying to contain any new disease that emerges.
How severe does this illness appear to be, especially compared to other coronaviruses it’s related to?
Saeed: So far, the case fatality rate of this virus is lower than that of SARS. However, it is premature to say anything with certainty at this point, given that the outbreak is still new.
Connor: As we learn more about the cases in China and elsewhere, the picture of how severe the infections are will become clearer. The virus will never be something that someone wants to get, and it will remain a serious risk for people that have other health problems. It is very early to draw strong conclusions, but at this point, it does not appear to be exceptionally lethal.
How effective are travel restrictions, such as the ones being enforced in central China?
Connor: Limiting the travel of people from an area that is clearly spreading the disease is a tough—but logical—decision from a public health standpoint. The results of China’s efforts will not be that the disease immediately stops being transmitted, but the best case scenario is that the restriction of travel slows the rise of new cases outside the Wuhan region, which will be very helpful in ultimately containing the outbreak.
Saeed: For viruses like this one, which spread through close contact, public health measures like isolating patients, tracking down their contacts, keeping them under watch, and screening healthcare workers—particularly those that work in the hospitals where coronavirus patients are attended to—are the best intervention strategies. Implementing strict screening and quarantine measures in hospitals [near the outbreak origin] are some of the steps to take immediately.
What can we expect in the coming days and weeks?
Saeed: Given how far the virus has spread, the number of cases is bound to increase in the coming days and weeks. Many in the field believe that the actual number of cases is way more than what is being reported. Research in the near future will try to address the exact origin and mode of how the virus spreads. A recent [study] from China has proposed snakes as the possible source of virus; however it has been received with much skepticism and I personally don’t believe that the [researchers] have provided any experimental evidence to prove that snakes at the Wuhan animal market might be the culprits. So, the jury is still out on this. Research efforts should also be focused on antiviral and vaccine development, so that any resurgence of the virus or future coronavirus outbreaks can be controlled.
How can people take precautions, along with the suggestions from the CDC?
Saeed: It’s normal for people to be alarmed about a virus we don’t know much about. People can protect themselves by avoiding interactions with people with apparent symptoms, washing their hands frequently, and immediately seeing the doctor if they have fever and cough.
This conversation was edited for length and clarity. This story was updated on January 29 to reflect new information.