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Possible Early Covid-19 Cases in China Emerge in WHO Probe
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© aly song/ReutersBEIJING—About 90 people were hospitalized with Covid-19-like symptoms in central China in the two months before the disease was first identified in Wuhan in late 2019, according to World Health Organization investigators, who said they pressed Beijing to allow further testing to determine whether the new virus was spreading earlier than previously known.
Chinese authorities performed antibody tests on about two-thirds of those patients in the past few months, according to the investigators, and said they found no trace of infection by the virus. But members of the WHO team probing the pandemic’s origins said any antibodies could have subsided to undetectable levels during the delay.
“Further studies are needed,” said Peter Ben Embarek, the food-safety scientist who led the WHO team, which wrapped up a four-week visit to China on Wednesday.
Team members said they urged China to conduct wider tests on blood samples collected in autumn 2019 around Hubei, the province that is home to Wuhan, to look for evidence about when the virus was first circulating. Chinese authorities said they hadn’t yet obtained necessary permissions to test samples, many of which are held in blood banks, WHO investigators said.
China’s disclosures to the WHO raise questions about the possibility that Covid-19—which has now killed more than 2.3 million people—was already spreading in China as far back as October 2019 and that earlier detection could have helped contain the outbreak before it became a global pandemic. Beijing says the first patient identified in China developed symptoms on Dec. 8, 2019.
Liang Wannian, head of the Covid-19 expert panel for China’s National Health Commission, said Tuesday that Chinese authorities had tested blood samples for antibodies, and checked medical records from 233 hospitals and clinics, but hadn’t found evidence of the virus spreading around Wuhan before early December 2019.
There had been no unexpected fluctuations in mortality levels from pneumonia or other illness in the preceding months, he said, and sales of cough and cold medicine didn’t provide useful indicators either.
Beijing has repeatedly sought to convey that it successfully managed an outbreak that began somewhere else. On Wednesday, a Chinese foreign ministry spokesman repeated Beijing’s assertion that there were signs of the virus spreading in other countries, including the U.S., in the second half of 2019, and urged them to invite the WHO to investigate.
The WHO said Tuesday that it was unlikely the virus escaped from a lab accident. The United Nations agency would now turn much of its attention to Southeast Asia, where it would like to scrutinize wildlife and animal-product supply chains, said team member Peter Daszak.
During the WHO delegation’s visit, investigators said they received medical records from Chinese authorities related to about 92 cases of people from the 233 institutions canvassed by Chinese authorities across Hubei. All 92 had suffered from pneumonia or other Covid-19-like symptoms. Chinese authorities subjected those patients to antibody tests in recent months.
About a third had died or refused to participate, said Dr. Embarek. The rest tested negative in serology tests that look for antibodies, he and other team members said.
“The numbers are not so important. What is important is that we don’t really know how reliable serology testing is to detect antibodies for SARS-CoV-2 more than a year after infection,” Dr. Embarek said. Another WHO researcher, microbiologist Fabian Leendertz, said the probability of finding antibodies that late would be low.
Marion Koopmans, a Dutch virologist on the WHO team, echoed that concern. “From what we know about serology, out of 92 cases you would at least have some positives,” she said. “Antibodies do clear. The levels go down, but less so in cases of severe infection.”
If the 90 cases included Covid-19 infections, it could help explain suspected coronavirus cases that researchers believe occurred in Europe and possibly the U.S. in November and December 2019.
In a recent study, Italian researchers found evidence of Covid-19 infection in a 4-year-old boy from the Milan area who was treated for respiratory symptoms and vomiting on Nov. 30, 2019. Researchers found RNA exactly matching part of the Covid-19 virus while retrospectively testing a respiratory specimen from the boy, along with specimens from other patients.
There might also have been a few cases of Covid-19 in the U.S. as early as in December 2019, weeks ahead of the first confirmed U.S. case on Jan. 19, 2020.
Researchers found possible Covid-19 infection in dozens of blood samples that had been saved for research. Just how many had contracted the new virus is unclear. It is more likely the pathogen was circulating elsewhere and imported to the U.S., rather than originating there, the researchers said.
Many scientists already believed that Covid-19 was circulating for some time before enough cases occurred at once in Wuhan to be detected. A modeling study last fall by researchers at the University of Arizona and the University of California San Diego suggested that the virus could have been present at low levels in Hubei as early as mid-October 2019.
Covid-19 symptoms can be similar to those of other respiratory diseases. It would be surprising if all 90 hospitalized patients had the new virus, but the cases are worth investigating, said Joel Wertheim, an evolutionary biologist at UCSD and an author of the study, which was posted on an online server and has been submitted to a journal for publication.
“Any confirmed case is informative, and any genome sequencing would be eye opening,” he said. “That would have the potential to change our understanding of how this pandemic got started.”
“This is so politically fraught,” said Maureen Miller, an infectious disease epidemiologist at Columbia University. “It was probably circulating much more widely than they believed…Doing antibody tests now, it’s too late. The ship has sailed.”
The WHO team said the virus most likely spread from a bat to another animal and then to humans, and not from a laboratory. They also posited that it could have entered China from another country, possibly via frozen products imported from other regions like Southeast Asia.
The Chinese government has denied that the virus could have come from a laboratory in Wuhan, a possibility for which the Trump administration previously said substantial yet undisclosed evidence existed. Beijing, for its part, has claimed the pathogen could have entered China via imported frozen food.
Dr. Liang said the Chinese team had reviewed unpublished studies from different countries that suggested the virus was circulating abroad weeks before its discovery in Wuhan. The WHO team said it was willing to look more deeply into such studies in other countries, such as Italy.
The U.S. said Tuesday it saw no potential origin other than in China and wanted to examine the underlying data from the WHO’s four-week mission.
The WHO had hoped to see antibody tests of any individuals in the Wuhan area hospitalized with Covid-19-like symptoms in the days before the first known case. Such tests could have indicated an infection—and provided a vital clue had they been conducted much earlier than last month.
The delay left the WHO team more dependent on blood samples taken around November 2019 and stored since then in Chinese hospitals or blood banks. But the available samples weren’t representative of the population, team members said, adding that they disproportionately included children, which offers little clue as to early Covid-19 transmission.
Further systematic studies of blood samples would help establish whether the virus was spreading in China before December 2019.
“It’s easy to suggest, but it’s not easy to do that,” Dr. Koopmans said, citing Chinese authorities’ statements that they hadn’t secured permission for such testing. “It’s something that was discussed and there was certainly an interest on the Chinese side.”
Thea Fischer, a Danish epidemiologist on the WHO team, also said she had recommended a systematic serological study on a representative part of the healthy population, such as those performed in several other countries, as one step that “would bring us closer to a potential circulation in the population earlier.”
She said she had asked to meet the Wuhan blood-donor center and established during the meeting that samples were available and that officials were open to the idea of a future joint study.
Researchers said it was also important to find whether any respiratory or other patient specimens were saved that could be tested for evidence of the Covid-19 virus.
Write to Drew Hinshaw at drew.hinshaw@wsj.com, Jeremy Page at jeremy.page@wsj.com and Betsy McKay at betsy.mckay@wsj.com
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