Coronavirus (COVID-19) Update 23 July

WHO Situation Report 184 for 22 July (released 23 July Brisbane, Australia, time)

Globally: 14,765,256 confirmed cases (202,726 new), 612,054 deaths (4,286 new)

Watching the progress at vaccine development is like riding a real roller coaster. One day the media is concentrating on the positive news from early stage trials with a particular vaccine candidate, the next day the news is full of disappointing news that antibodies to the novel coronavirus drop quickly in people who have been infected.

I watched two conversations on Bloomberg this week that presented the best available opinion on where we presently stand. The first was with Richard Horton, the Editor of “The Lancet”, the pre-eminent medical journal, where he said that the Oxford vaccine trial went about as well as could be expected. He cautioned, however, that it is at a very early stage, and there may be other challenges faced, so best to keep expectations well in check. The second was with Dr Vasant Narasimhan, the CEO of Novartis, whose background is in vaccinology, who said that they are not going to risk rushing the vaccine because the dangers are too serious to contemplate, and data checking would take around 6 months from the completion of trials.

I had not thought of it until he said those words, but it is difficult to overstate what is at stake here for the vaccine companies who have been under attack from the global anti-vax campaign. A timely, well tolerated and effective vaccine would go a long way towards dispatching the anti-vaxxers for once and for all. On the other hand, a problem with a vaccine that is administered to large swathes of the population would be enormously damaging to the industry, especially those companies involved, and would be a boon to the anti-vaxxers. Those dangers for the vaccine companies will ensure that time will be required to ensure that all safety boxes are properly ticked and verified before any vaccine is administered en masse.

On an equally pertinent issue – yes, believe it or not there is another issue as important – since uttering “aloud” in my previous update on 30 June my concerns over whether some of our food animals may be susceptible to infection by the novel coronavirus, I have been trawling through the literature.

One development in this area was of particular concern – a mink farm in Spain culled 100,000 animals when it was discovered that 87% of animals were infected with the novel coronavirus SARS-CoV-2 along with 7 workers. The virus is believed to have entered the farm with an infected worker, and there is concern that the virus can be transmitted both from humans to mink, and from mink to humans. The same report stated that 25 mink fur farms in the Netherlands were found to have infected animals, along with 3 farms in Denmark.

This clearly is a very serious issue as it highlights the potential for other animals to act as reservoir hosts for SARS-CoV-2 and to reseed new outbreaks in humans. This is possibly the most troubling finding for COVID-19 in recent months, and that is likely why it is not being widely discussed in the mainstream.

While that is serious enough, if food animals are found to be susceptible to infection then the situation would be worse by several orders of magnitude because difficult decisions would need to be made about whether to cull infected populations, potentially causing food shortages, and it opens up the issues of food borne transmission.

Now I know nothing about the mink industry, but it would be interesting to know whether there have been outbreaks of COVID-19 in slaughter houses which processed mink and what happens to the meat which I assume is a by-product of their main purpose of fur production.

Before discussing these implications, I should spell out that early technical research on the way that SARS-CoV-2 enters the cells of its hosts (i.e. our cells) suggested that the virus would have a relatively wide host range – i.e. these studies suggested that it could infect a large range of mammal species. These studies suggested, however, that two important food animals, chickens (obviously not a mammal) and pigs, were unlikely to be susceptible to infection. However, cattle, sheep and horses were considered highly likely to be susceptible.

These studies are predictive in nature, and real world studies are required to test those predictions and they can include observations and analyses on wild and farmed populations of animals, and through experimental infections studies using both unnatural routes (i.e. inoculation by injection) or natural routes (i.e. inoculation onto membranes, or cohabitation with infected animals).

As I stated in previous reports, biosecure facilities for testing large animals for susceptibility to serious pathogens are not common but a study reported in early July failed to produce infections in pigs and chickens, but established strong infections in ferrets and fruit bats. These results are consistent with the earlier predictions.

Now I do not want to go into deeper detail than this, but this gives the reader enough background to really have a clear understanding of the risks that this issue present. However, if the reader wishes to conduct further research then I suggest clicking on that link above and reading especially the box “research in context”. The reference list at the end of the paper is a good start to finding additional technical information. Searching terms such as “SARS-CoV-2 host range”, “transmission studies” and “ACE analysis” (ACE refers to the mode of entry to host cells to initiate infection) will provide links to most available literature.

Obviously, if it is shown that beef and/or sheep or other meat animals are susceptible to infection then that really opens up the risks associated with dispersal of the virus geographically and over time in frozen meat. The intensity of farming is always related to the risk of disease outbreak, so beef feedlots would be especially at risk if cattle are susceptible.

Importantly, real world observations and transmission studies do seem to be confirming those predictive studies.

The lack of open discussion on this topic should not be interpreted that this is a non-issue. In reality, it is such a serious issue that Governments will avoid discussing it until it becomes necessary by events. When I worked at Biosecurity Australia, the extreme public sensitivity over the idea of pathogens being present in food – even when there was no chance that the pathogen could infect humans – was foremost in the crafting of all media releases.

If it becomes clear that some of our most widely consumed food animals are found to be infected by the most serious human pathogen to emerge in a century, then reputational damage to that industry would be enormous. That is what is at stake here (too serious for obvious puns!)

I was already concerned by the potential for contamination of processed meat by infected workers. But this suggests that it is entirely possible that the route of transmission might be the other way around, also – workers being infected by meat from infected animals. (Remember my video when that was one of the most credible pathways for the virus’ initial jump into humans.)

The broad host range of SARS-CoV-2 serves to emphasise just how unwise it is to allow this pathogen to spread in human populations without doing everything within the scope of our modern scientific and biosecurity capabilities to impede it and aim for elimination. If it becomes endemic in reservoir host species, then COVID-19 will only ever be managed in humans by effective vaccines.

Finally, just imagine the value to Australia of eliminating COVID-19 if it were found that cattle and sheep are susceptible to infection. I would not like to be a conservative Government minister explaining to the bush that the opportunity to export meat from a certified COVID-19-free region was squandered. Now that really is a major economic and political benefit from an elimination strategy!

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© Copyright Brett Edgerton 2020