Six weeks after announcing the appearance of a new, highly contagious and sometimes lethal virus, experts say China is still not sharing important data that could help contain the epidemic.
"As countries are trying to develop their own control strategies, they are looking for evidence of whether the situation in China is getting worse or better," said Jennifer Nuzzo, a senior scholar at the Johns Hopkins Center for Health Security.
But that evidence is not forthcoming.
"We still don't have very basic information," said former U.S. Centers for Disease Control and Prevention chief Tom Frieden, who currently heads public health nonprofit Resolve to Save Lives.
As a team from the World Health Organization arrives in China to help respond to the COVID-19 outbreak spreading out of the central city of Wuhan, "we hope that information will be coming out," Frieden said.
"The next few days will be key," he added.
Beijing has not accepted the CDC's offer to send top experts.
Mike Ryan, head of WHO's health emergencies program, did not specify nationalities of the team members at a press conference Thursday. "But I can assure you the team is top-class scientists from all over the world and all of the relevant countries who can contribute to an endeavor such as this," he said.
"We are a little disappointed that we haven't been invited in and we're a little disappointed in the lack of transparency coming from the Chinese," Larry Kudlow, the director of President Donald Trump's Economic Council, told reporters Thursday.
Behind the curve
China is releasing a daily count of newly identified cases, but not the date when those patients became ill. That's important because without the date of symptom onset, epidemiologists can't tell if an epidemic is growing or waning. The daily case count indicates when testing labs are processing samples without revealing much about the course of the outbreak, experts note.
When Chinese officials changed how they diagnose the disease on Thursday, it was impossible to tell if the 13,000 new cases Beijing reported actually represent a jump in infections because Beijing hasn't reported dates of onset. WHO's Ryan said some of those cases go back to the beginning of the epidemic. But WHO doesn't know which ones.
China is not routinely releasing data on patients' ages and who gets the most severe disease. It's not clear how many people who were tested came back positive. It's not known how many people who are infected don't get tested.
"We know some are missed, there's no question about that," said Frieden from Resolve to Save Lives.
"But is it 10 times as many? Five times as many?" he asked. "We just don't know."
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Health care workers are at extremely high risk of infection in any outbreak. WHO usually lists infections among this important group in its situation reports. But Beijing has reported very little about how health care workers are faring.
Researchers in Wuhan have published one study that said 40 out of 138 hospitalized patients were health care workers who contracted the illness in the hospital.
"That was really the first public indication that health care worker infections had, in fact, occurred," Nuzzo from Johns Hopkins said. "That, I think, is a really glaring omission."
Frieden partly blamed the lack of data reporting on a "fog-of-war experience in an overwhelming outbreak." The volume of patients has vastly exceeded the capacity of the health care system.
But the lingering question, he added, "is whether they're holding back some information."
Better than SARS
Early in the outbreak, Chinese authorities pressured doctors who spoke publicly about the new disease.
Beijing drew global condemnation for withholding information during the 2002-2003 outbreak of severe acute respiratory syndrome.
This time, officials have praised Beijing for reporting the COVID-19 outbreak much more quickly and for rapidly releasing the virus's genetic code.
Chinese scientists have published a series of "elegant" studies in top medical journals outlining some important details of the disease, Nuzzo noted.
"I don't want to paint a picture of a country that's absolutely refusing to turn over data because they're clearly cranking out papers," she said.
But critical information is still lacking, and in a serious outbreak of a new disease, she added, data should be shared as widely as possible as soon as possible.
"The basic concept is tell people what you know when you know it," Frieden added. "And if you don't know something, indicate how are you going to find that information out."