Coronavirus: China plans to test Wuhan blood samples from before outbreak
- Research could uncover earlier cases prior to the first known patient in December 2019
- Chinese scientist says it can only begin once a two-year statutory storage period has passed
The research will be conducted in Wuhan, where Covid-19 was first identified in late 2019, and can only take place once a two-year statutory blood storage period has passed, according to scientist Liang Wannian, who led Chinese experts during a WHO-backed inquiry into the origins of the virus earlier this year.
But it remains unclear whether other stored blood samples from the surrounding province or elsewhere in the country will also be screened or preserved for research after the two-year period is up.
Liang said the testing of stored blood samples could help identify Covid-19 infections prior to the first known patient, a case recorded on December 8, 2019. This case is not considered to be “patient zero”.
“The Chinese side is currently organising relevant experts and organisations to prepare for such work and we are formulating the methods and implementation plan for the blood testing in advance,” Liang said. “When the blood samples can be tested after the storage period, we will carry out the relevant testing and share any outcomes with Chinese and foreign experts.”
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Before the end of the period the samples could only be used to settle medical or legal disputes, for example if there was a question of blood contamination following a transfusion, Liang said.
The proposal, according to National Health Commission deputy minister Zeng Yixin, did not follow recommendations made following the initial WHO mission into the origins, in particular because it included a provision for research into whether the virus was the result of a laboratory leak.
The WHO’s release of the plan to member states last week came as the UN agency is under pressure to advance its work to understand how the pandemic began.
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Uncovering earlier and as yet unknown Covid-19 patients is viewed as a critical part of understanding where the virus came from. Serological testing – which looks for antibodies specific to a certain virus in the blood – can help scientists with access to stored samples look into the past and understand whether people or animals were infected at different points in time.
The Wuhan research was put in motion during the earlier WHO-led mission to the city, when international and Chinese scientists met Wuhan Blood Centre officials and recommended screening for Covid-19 antibodies in blood donors from September to December 2019.
“This could be expanded to include other blood centres in China and other locations worldwide, focusing on the six months (at least three to four months) period before the first cases in each location were identified and ideally using a common laboratory testing approach,” said the report, which was released in March.
Liang’s comments appear to confirm that the blood sample testing will go ahead in Wuhan, but he did not says if it would take place in other parts of China.
In May, Danish epidemiologist Thea Fischer, who was part of the WHO mission to Wuhan, said it was “promising” that the Wuhan Blood Centre had agreed to postpone the scheduled destruction of samples after two years in anticipation of further research.
But she expressed concern such samples could be destroyed in other cities that may also have relevant clues. “It’s really like the clock is ticking and we need to move on with these studies,” she said at the time.
Serological studies, while not as precise as other methods, have been used in a number of countries to look for evidence of earlier circulation of Covid-19.
Chinese officials have repeatedly pointed to serological studies suggesting the virus was spreading in Europe in the autumn of 2019, before it was identified in China, as evidence that it may not have emerged within its borders.
Similar studies of samples from that period within China have not been made public.
