NY Times:
The virus may have been in Washington State for weeks.
As Washington State declared a state of emergency over the new coronavirus, researchers who studied two cases in the state say that the virus may have been spreading there for weeks, suggesting the possibility that up to 1,500 people in the state may have been infected.
The state became the site of the country’s first coronavirus death on Saturday, at a time when President Trump issued new foreign travel warnings and restrictions in an effort to stop the spread of the virus, while also urging calm among members of the public.
The number of confirmed cases worldwide had reached nearly 87,000 as of Sunday, with more than 7,000 cases outside mainland China, where the outbreak began late last year. The virus has now been detected in at least 60 countries.
With 71 cases confirmed in the United States, the Food and Drug Administration announced this weekend that testing for the coronavirus would be greatly expanded in the country, a move that is expected to improve the pace of detecting infections and help identify patterns of suspected or confirmed cases.
In Washington State, researchers compared two cases in the hopes of gaining such insight. One case, which last month became the first in the United States, appeared in a patient from whom health officials took a sample on Jan. 19. Another case that surfaced in the region last week probably descended from it, based on an analysis of the virus’s genetic sequence.
The findings suggest that the virus has been spreading in the community for close to six weeks, according to one of the scientists who compared the sequences, Trevor Bedford, an associate professor at the University of Washington.
If that is true, it could mean that 150 to 1,500 people “have either been infected and recovered or currently are infected now,” said Mike Famulare, a researcher at the Institute for Disease Modeling in Bellevue, Wash., who performed the analysis. Those cases, if they exist, have thus far been undetected.
Many of those people might not yet be contagious, Dr. Famulare said.
His estimation was based on a simulation using what scientists have learned about the incubation period and transmissibility of the virus. He characterized his estimate of community cases as a “best guess, with broad uncertainty.” Another method, based on census data and estimated sampling, produced similar results, he said.