China says coronavirus can spread before symptoms show — calling into question US containment strategy

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China’s health minister Ma Xiaowei made a startling statement Sunday about the Wuhan coronavirus: He said people can spread it before they become symptomatic.

“This is a game changer,” said Dr. William Schaffner, a longtime adviser to the US Centers for Disease Control and Prevention.
It’s much harder to contain a virus — to track down a patient’s contacts and quarantine them immediately — if the patient was spreading the disease for days or weeks before they even realized they had it.

“It means the infection is much more contagious than we originally thought,” said Schaffner, an infectious disease specialist at Vanderbilt University Medical Center. “This is worse than we anticipated.”
Ma didn’t explain why he thinks the virus can be spread before someone has symptoms. If the Chinese health minister is right — and there are those who doubt him — that means the five confirmed cases in the United States might have been infectious while traveling from Wuhan to Arizona, California, Illinois and Washington state, even if they had no symptoms at the time.
On Sunday, Dr. Nancy Messonnier, director of the US Centers for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases, said the risk to the American public for contracting this virus continues to be low.
“We at CDC don’t have clear evidence that patients are infectious before symptom onset, but we are actively investigating that possibility,” Messonnier said.
“We need to be preparing as if this is a pandemic, but I continue to hope that it is not,” she added.
The Wuhan coronavirus has killed more than 50 people in China and infected thousands there, and spread as far as the US, France and Canada.
‘We’re going to have to reevaluate our strategy’
US health officials believe the Wuhan virus has an incubation period of about two weeks, CDC officials said Friday during a media briefing.
“Based on what we know now about this virus, our concern for transmission before symptoms develop is low, so that is reassuring,” Dr. Jennifer Layden, an epidemiologist with the Illinois Department of Health, said at the Friday briefing.
NIH doctor wants US to inspect Chinese data
The United States’ top infectious disease doctor wants a team of CDC disease detectives to go to China and check on these crucial questions about how the Wuhan coronavirus is spreading.
But there’s something stopping them: China first has to invite the CDC.
“Up to now, to my knowledge, we have not been invited,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health, said Sunday.
NIH and CDC are separate divisions of the US Department of Health and Human Services.
The implications of Ma’s statement that the coronavirus is transmissible before symptoms are so important “that in my mind it’s absolutely critical that we ourselves see the data, because what goes on over there has implications for what happens here,” Fauci said.
He added that to his knowledge, the Chinese did not tell US health authorities that the virus could spread before someone is symptomatic, a crucial aspect of any disease investigation. He said he learned about it after reading a CNN reporter’s email.
Fauci said that CDC disease detectives would need to see precisely how Chinese health authorities have gathered their data and how they came to their conclusion.
“To my knowledge, we have not seen the precise minute, granular data and how they collected it,” he said. “We need to get to the real bottom line of how they collected their data and see if it’s valid.”
“The Chinese have good people. I don’t want to impugn their capabilities,” Fauci added. “But when it’s something as important as this, our people who are trained epidemiologists need to go over their data and the best way to do that is go there and see how they’re collecting it.”
CDC’s Messonnier said Sunday the CDC has staff in China, but the team is not directly involved in the Wuhan coronavirus response. The agency hopes to have “additional engagement” on the outbreak in China in the coming days, she said.
In a tweet on Sunday, World Health Organization Director-General Tedros Adhanom Ghebreyesus said, “I am on my way to Beijing, [China] to meet with the Government & health experts supporting the #coronavirus response. My @WHO colleagues & I would like to understand the latest developments & strengthen our partnership with [China] in providing further protection against the outbreak.”