Jan. 28, 2020 -- With a new coronavirus sickening thousands across China, researchers who specialize in tracking the spread of infectious disease are modeling its movements. They’re asking just how widespread the illness could become, now that cases have been confirmed in 17 other countries.
“We’ve already lost control of it in China,” says Michael Osterholm, PhD, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
He says the quarantines in major Chinese cities have probably had limited impact.
“The idea that we could create this seal around China is just totally unrealistic,” he says. “I think at that point, you have to assume we’re going to see widespread transmission around the world.”
Likewise, Scott Gottlieb, MD, former commissioner of the FDA, said in an op-ed for CNBC that “global spread appears inevitable.”
On Tuesday, the CDC announced that it would expand its surveillance of travelers. Enhanced screening will take place at 20 airports, up from the five airports that are now doing enhanced screening.
The CDC also took steps to limit travel to China, asking people to reconsider any trips there and not go at all unless it was absolutely necessary.
The latest report from a team from the MRC Centre for Global Infectious Disease Analysis at Imperial College London estimates that based on the frequency of international travel from Wuhan, there were as many as 100,000 people infected as of Jan. 26, a number that’s far higher than official case counts.
Osterholm thinks the higher estimate is probably on target. That’s because the official counts depend on testing, and not everyone is being tested.
“Right now, testing is extremely limited in most locations,” he says.
In the United States, the CDC has posted the blueprints for a test for the 2019-nCoV virus, and it is working to send testing kits to state health departments. It will be at least a week before tests are available outside of CDC headquarters in Atlanta.
Charting the Spread
The Imperial College London team has also estimated that right now, every infected person spreads the disease to between 1.5 and 3.5 other people. That’s the basic reproduction number, or R0. At 2.6, the estimated R0 for 2019-nCoV is roughly the same as for its cousin, severe acute respiratory syndrome, or SARS. Experts say they don’t have a good handle on how often infection with the virus turns fatal, but so far, it appears to be less deadly than SARS. From 2002 to 2003, the SARS outbreak killed nearly 800 people.
The R0 number changes as control measures -- like isolating sick people -- are put into place. The goal is to get this number low enough so that person-to-person transmission is limited. An R0 above one means sustained person-to-person transmission of an infection.
“In general, you want to get the R0 below 1; that’s how you get a disease under control,” says Nancy Messonnier, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases.
To bring the R0 down, the World Health Organization says it is critical to limit person-to-person transmission, by following the close contacts of infected people and protecting health care workers who treat patients. To do that, people who get sick have to be identified early in their infection. That will require more education about risk and symptoms, and more rapid testing of possible cases.
So far, only a handful of 2019-nCoV cases have been confirmed in the U.S. All of them have come into the country with travelers returning from Wuhan.
As of Jan. 27, the CDC had 110 people under investigation in 26 states. Of those, five people have tested positive for the virus, while 32 have been cleared. Test results on 73 others are pending. Messonnier said some of those suspected cases were close contacts of infected travelers.
The CDC has said it expects numbers of suspected and confirmed cases to increase. It’s asking people who have traveled to China to seek medical care if they have symptoms like a fever or a hard time breathing.
And researchers are rushing to get a vaccine that could protect against infection into clinical trials.
Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, says the National Institutes of Health is working on better tests, antiviral medications to treat the infection, and a vaccine to protect people from being infected in the first place.
“We’re proceeding as if we will have to deploy a vaccine,” he said at a news briefing. “In other words, we’re looking at the worst scenario -- that this becomes a bigger outbreak.”
Addressing the media Tuesday, Alex Azar, secretary of the U.S. Department of Health and Human Services, reminded reporters that so far, only five cases have been diagnosed in the U.S. and that the risk to Americans so far is very low.
“The playbook for responding to an infectious disease outbreak is relatively simple,” he said. “You identify cases. Isolate people. Diagnose them and treat them. Then you track down all the contacts of the infected person, and you do the same with those people and the same with contacts of contacts, if necessary.”
Azar said that was the kind of hard work being done to contain the outbreak in the U.S.
‘I Think Now We’re Ready for It’
“I think the numbers will go up, but I don’t think we’re going to see anything like what we’ve seen in China here in the United States,” says Peter Hotez, MD, PhD, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston.
He says the warning from China gave the U.S. and other countries a leg up.
“I think now we’re ready for it. We know when someone comes in from China. If they have symptoms, they’re being monitored and placed in quarantine,” he says.
Right now, as soon as a health care provider suspects that someone could be infected, they are being told to put a mask on the person and isolate them in a private room until testing for the virus can be done.
Hospitals are keeping people who have been confirmed to have the virus in isolation until they recover. In China, where the virus is most prevalent, officials are taking the extra step of building separate health care facilities to treat infected patients.
One thing that could change that picture is if those who are infected could transmit the virus before symptoms appear -- the so-called incubation period. That would make new infections harder to stop.
A Chinese health minister made that claim over the weekend, and doctors in Germany said a recent case there was transmitted by a person who didn’t have symptoms. But Messonnier and other experts say they still aren’t sure the virus can spread this way.
“There have been isolated reports of asymptomatic infection from several countries. We’re looking at that data closely,” Messonnier says.