None of the hypotheses about the origins of the SARS-CoV2 virus have been discarded and the World Health Organization (WHO) origins mission might be expanded to include other experts to take forward new areas of research, WHO Director General Dr Tedros Adhanom Ghebreyesus told the body’s bi-weekly media briefing on Friday.

“I wish to confirm that all hypotheses remain open and require further analysis and studies, some of that work may lie outside the remit and scope of this mission,” said Tedros about the mission which returned earlier this week from a month-long investigation in China.  

Before leaving China on Tuesday, the expert team told a media briefing that it had identified four hypotheses about the origin of SARS-CoV2, including that it originated in a laboratory, which they deemed “unlikely.”

The most likely cause was that the virus was transmitted from bats by an intermediary animal source, while bats as the direct source of the virus or it being transmitted by frozen food were the two other theories.

Team leader and WHO food safety expert Dr Peter Ben Embarek told the briefing that he regarded the mission as a success as it “came to a better understanding of the early days of the pandemic in Wuhan and identified areas for further analysis and research.”

Reacting sharply to a question about whether it could have found more evidence had it gone to Wuhan earlier, Ben Embarek said it was “not a mission to go and chase an animal in the market or chase a patient somewhere.”

“In February, it would have been impossible to be in Wuhan because Wuhan was in total lockdown in the middle of fighting the disease, and that took a few months before the city was reopened and the business returned to normal,” said Ben Embarek.

“Many of these studies have involved thousands of people and researchers in China to conduct. And if we had gone much much earlier we wouldn’t have had the same material to look at,” he added.

Over 97,000 Patient Records Assessed

The team found no evidence of the virus in Wuhan before December. Elaborating on this, Professor Marion Koopmans, team member and head of the department of Viroscience at the University of Rotterdam, said that the team had examined mortality statistics to see whether they could identify any unusual death patterns, as well as reports of influenza.

They assessed 97,000 patients’ records and narrowed down 92 cases of COVID-like symptoms in Hubei Hospital – but none of the patients that they could trace tested positive for the virus, although a few could not be traced or had died.

“All the potential cases were tested for COVID-19 and were negative, the one question that is out there is, can you still rule that out, a year after an infection, the serology is negative then,” said Koopmans, who added that there were ongoing discussions with China about the team getting access to blood banks to test samples.

Ben Embarek said that the mission had been “successful in many ways,” and had provided evidence that there was “no widespread and no large cluster of the disease in Wuhan, or elsewhere, around Wuhan, in the months prior to December 2019.”

“We have been able to demonstrate that there was substantial circulation of the virus in Wuhan in December 2019, we’ve been able to link genetic sequences of different patients across the city in December with their physical location in and outside the market across the time, from early December to end of December,” said Ben Embarek.

“We have a much better understanding of what happened in the market, the role of the market, we have also been able to trace back all the suppliers of different wild animal products into the market as a potential clue for further studies,” he added.

The team’s findings from their mission and the studies that were conducted will be written in a summary report, due to be published next week, with the full report following in the coming weeks, said Tedros.

Vaccines Likely to Protect Against Severe Disease – Even With Variants

In response to a question about whether the AstraZeneca vaccine would still be effective against variants in the light of the small South African study that showed it had little effect against the 501.V2 variant, WHO Chief Scientist, Dr Soumya Swaminathan, said the body still had hope that the vaccine could prevent “severe infection and death.”

“The trials that have been done so far in South Africa, as well as in Brazil with different candidates have shown complete protection against severe disease and hospitalisation,” said Swaminathan. 

“Our goal in the first wave of vaccinating people is to protect those at highest risk from severe disease, hospitalisation and death. So vaccines are protecting against getting severely ill, even though they may not protect completely against getting infected or mild disease,” she added.

She also urged people who have been vaccinated to “take precautions, to wear a mask, to wash hands, to maintain the physical distancing, to really reduce the risk” as it is still unclear whether they can pass on the virus to others.

However, Dr Bruce Aylward, WHO Expert Adviser, said confirmatory studies would have to come from countries that had these variants.

Vaccines to be Airlifted to Ebola Outbreak in DRC 

Two of the three people infected with Ebola in the Democratic Republic of Congo died, but the source of the outbreak has not been identified, Dr Michael Ryan, WHO Executive Director of the Health Emergencies Programme, said. 

Extensive contact tracing of the three has already taken place, and “over half of those contacts were vaccinated in the previous Ebola outbreak, most of those are actually health workers who were previously vaccinated,” said Ryan, who added that 16,000 vaccines would be airlifted to the affected area from Kinshasha over the weekend and there were 400 doses of monoclonal antibodies to treat those who might get infected.

Image Credits: CGTN.