There are no surprises here in the report. The most likely explanation for the pandemic was always that it emerged in a similar way to which SARS did back in the early 2000s- that is, it involved the jumping of the virus from an animal host to humans. There really wasn’t any plausible reason for us to think anything else had occurred given what we know about new pathogens and their origins.

Having said this, and not downplaying the considerable expertise of those who are part of the fact finding mission and their intentions, and the fact that some useful information would have been gathered, as a scientist and epidemiologist I do remain sceptical as to the value of visiting Wuhan a year after the start of the pandemic. This international investigation should have been able to occur at the beginning of the pandemic, and it is a missed opportunity that this was not able to be organised earlier.

If this puts some of the conspiracy theories to rest while we focus on the job at hand in controlling the pandemic, then this has probably made the international mission worth it. Clearly there is more work that needs to be done to understand as much as we can about the origin of this virus that has caused so much upheaval in the world.

The team does not reveal anything substantially new to what was already speculated by scientists - which is about the natural origin of the virus and bats as a possible ancestor, with an intermediary animal species as the host which infected humans.  We already knew the bat, which carries the closest relative, is not in Hubei province, but in Yunnan, which is thousands of miles away. A similar virus caused severe pneumonia in miners in that area in 2012, and the Wuhan Institute of Virology had samples of that virus. The WHO team is not able to pin point any intermediary animal species. The speculation about the market and frozen foods presupposes that the outbreak originated there - which is not clear. They admit half the cases did not visit the market. 

I am surprised that they concluded the outbreak started in December and not earlier.  There is now serological data from the US and Europe that shows the virus was already circulating in those regions by December 2019, which does not fit with the WHO postulate that it was not circulating widely prior to December.  We have also heard about outbreaks of a flu like illness at the world military games in October in Wuhan, and also of possible “patient zeroes” identified in mid November 2019, including in one study which we published.

A thorough analysis would need to look at stored sera between October and December 2019 from athletes at the World Military Games. We also need to understand why archived Spanish wastewater samples were positive for the virus from March 2019. In epidemic investigation it is important to study outlier data, and not to dismiss outliers that do not fit our beliefs.  

They quickly dismissed possible unnatural origins, which was expected, given the political sensitivities, not just for China, but for the world.  They do not provide any evidence for dismissing a lab leak.  If a lab accident were the source, it would have huge ramifications globally, including for the regulation and practice of virology into the future.  One of the WHO team was part of a non-profit organisation which provided funding for the bat virus research done at The Wuhan Institute of Virology prior to the pandemic.

The virus may well have emerged in nature, but a lab accident is also a possibility, as the BSL4 lab in Wuhan was studying bat coronaviruses, including the virus found in the miners outbreak in 2012.  Other biosecurity experts share my concerns as outlined here.

We may never know the origins of this virus.

The results presented indicate that the most likely source is linked to the market chain of wildlife species which facilitated the spill-over to humans. There is historical precedence for this with regards to SARS in 2003. This suggests that SARS-CoV-2 is not strictly a zoonoses but rather an emerging infectious disease of animal origin and thereby, to break the cycle of emergence, the wildlife market chain should be the targeted.

The molecular epidemiology findings presented by the WHO team are still preliminary in that sequences from different suspect species such bats and pangolins are not similar enough to indicate a direct link for spill-over.

It is possible that a re-assortment event may have occurred in an intermediary species present in the market chain which is currently unknown and more research is needed. What we know is that feline species and mink are very susceptible to SARS-COV-2 but that does not mean they can be a reservoir to humans. Indeed most transmission is between humans and control should consider targeting human populations.

However, the findings indicate that the wildlife market chain is indeed a biosecurity weak link in the origins of SARS-CoV-2 and robust biosecurity interventions should be implemented. This could involve a similar policy framework that was implemented for avian influenza control in poultry markets known as the “1110” policy, coupled with ongoing surveillance taking a One Health approach.

It is positive to see investigations starting into the origins of the Covid-19 pandemic.   As expected, no conclusive or novel  findings have been made by the panel after their 2 week visit to China. This preliminary WHO report does not change the existing widely held narrative on the origins of the virus. 

It does however go further than many might have expected in emphasizing two key assertions previously made by the Chinese government that the virus source of the pandemic may lie outside of China, and the possibility the transmission into China occurred via frozen food. 

The scientific evidence behind both these assertions by the WHO panel remains unclear, beyond relatively weak data already in the public domain, but it is possible the panel has access to additional information not currently publicly available to explain why they are emphasizing these particular claims, which have already been challenged by others.  

Similarly while supporting an intermediate host transmission as the most likely source of the outbreak, no additional guidance has been provided as to what this potential vector could be, or to explain why this has so far proved impossible to identify. Until this natural source of the virus can be found, this will always leave open other possibilities, no matter how remote, that the virus did not have a completely natural origin. 

This is a vitally important point to establish as if this pandemic was due to a natural transmission event then we can expect multiple further transmissions of similar related coronaviruses from the same animal host to humans over coming years, just as we have seen for MERS coronavirus, Ebola, avian influenza etc.  Alternatively, if it was a non-natural event then the likelihood of a future related outbreak should be minimal assuming that any activities that could have led to the generation of the virus have ceased.

So this WHO panel report brings little additional clarity to the issue and leaves us no closer to knowing the origins of the SARS-CoV-2 virus. Further research is clearly warranted.