The director of the Centers for Disease Control and Prevention on Friday defended the agency’s failure to find early spread of the coronavirus in the United States, noting that surveillance systems “kept eyes” on the disease.
“We were never really blind when it came to surveillance” for covid-19, the disease caused by the virus, CDC chief Robert R. Redfield said. Even if widespread diagnostic testing had been in place, it would have been like “looking for a needle in a haystack,” he said.
Redfield was among three CDC officials who spoke with reporters Friday about a comprehensive analysis by the agency that found the coronavirus began spreading in the United States as early as the second half of January, eluding detection by public health surveillance systems that help monitor for early signs of novel contagions.
Reporters who received the report had requested to speak with experts. It was the first such CDC briefing in nearly three months.
The report looked at public health surveillance data, confirmed cases of covid-19 and the transmission of distinct genetic strains of the virus. The results are consistent with other scientific studies that have described a two-stage viral attack that began in January on the West Coast with the coronavirus introduced by travelers from China and continued in February as travelers from Europe brought the virus to the East Coast. Most of the virus spreading in the United States can be traced to the introductions from Europe.
Redfield said the findings debunk speculation the virus was circulating months earlier.
“There was one opinion that was circulating that in November, December and January, there was, if you will, significant seeding of the nation,” Redfield said. “And what this data clearly shows is by four independent lines of evidence, that the early introduction of this virus in the Northwest and Northern California was sometime between the second week of January and the second week of February.”
Jay Butler, CDC’s deputy director for infectious diseases, said the findings also show that transmission was limited and not as widespread as some experts have suggested.
Addressing the botched CDC rollout of test kits that experts say allowed the virus to take hold and spread quickly, Redfield said diagnostic testing would have made little difference at that time. When U.S. cases were first detected in January and February, health officials identified about 800 high-risk individuals who had been in contact with infected patients. Only two of those people tested positive, he said.
Still, that doesn’t mean officials should simply wait for the needles “to replicate themselves until they are the haystack,” said William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.
“There’s a succession of missed opportunities here,” he said. “Surveillance at the time was wholly inadequate to the task of catching a pandemic virus of this sort, whenever it was introduced.”
Michael Worobey, a University of Arizona evolutionary biologist who is lead author of a