'Great concern' on virus

Public health officials say they face long list of coronavirus unknowns.

WASHINGTON — China has ordered an unprecedented quarantine of more than 50 million people. It has closed schools and shut down live animal markets. Airports across the globe are screening passengers coming from the world’s most populous country.

What’s happening

But three weeks after the new coronavirus emerged as a health crisis, experts can’t yet say whether these efforts will succeed at containing an infection that now threatens at least 17 countries.

Some early signs are discouraging: Six countries, including China, have confirmed human-tohuman transmission of the infection. Those include four cases in Germany connected to a single person — a worrisome sign for containment of the disease. Cases in China continue to multiply, and 5 million residents of Wuhan, where the virus originated, already have left the city, some of them surely carrying the disease.

But so far, the mortality rate is less than the rate of other severe respiratory coronaviruses: In China, where 5,974 people are infected, 131 have died through Tuesday. That is a high rate but far less than the fatality rate of SARS and MERS. And countries like the United States that quickly began screening travelers, isolating sick people and tracing their contacts have just a handful of cases each. There have been no fatalities outside China.

Public health officials said Tuesday that they are grappling with a long list of unknowns that will determine how successful they are in limiting the toll of the widening outbreak. Those questions include how lethal the virus may be, how contagious it is, whether it is transmitted by people who are infected but show no symptoms and whether it can be largely contained in its country of origin.

“It is very striking how quickly the numbers are going up,” said Trish Perl, chief of infectious diseases and geographic medicine at the University of Texas’ Southwestern Medical Center, who has fought other respiratory virus outbreaks, including SARS and MERS — severe acute respiratory syndrome and Middle East respiratory syndrome.

How experts are helping

China agreed Tuesday to allow a World Health Organization team of experts into the country to study the coronavirus, officials of the

United Nations agency said after a meeting between the organization’s director general and Chinese leader Xi Jinping.

It was unclear whether the team would include experts from the U.S. Centers for Disease Control and Prevention.

But several nations continued to pursue or consider evacuating their citizens from Wuhan, including France, South Korea, Morocco, Britain, Germany, Canada, the Netherlands and Russia.

Yet for all the action taken, even the near future remains uncertain.

“There is a real possibility that this virus will not be able to be contained,” said former CDC Director Tom Frieden, who oversaw the responses to the Ebola and Zika outbreaks.