Friday, 18 September 2020

Belarus, T-Cells and COVID-19

There are a couple of interesting articles in the BMJ this week about the old Miley Cyrus, including one involving a rare mention of Belarus. Sweden's relatively laissez-faire attitude towards Covid grabbed the world's attention but Belarus took an even less restrained approach. In Sweden, it's been the epidemiologists calling the shots. In Belarus, it's the dictator. But both have ended up being a sort of control group.

Belarus isn't the most open society, to put it mildly, and its data are questionable. Its daily Covid death count has been suspiciously consistent, nearly always between four and six. No doubt the numbers have been massaged, but Belarus is not such a closed society that word wouldn't get out if its health service was collapsing and people were dying left, right and centre - which is what the likes of Prof Neil Ferguson would have predicted given that it didn't come close to locking down.

According to the BMJ, Belarus has 'one of the lowest [COVID-19] death rates in Europe' and the author is forced to come up with a bunch of post hoc rationalisations for this. Just as the experts suddenly remembered that Sweden has a relatively low population density after the predicted catastrophe failed to materialise, we are now told that Belarus has a large hospital capacity, has done quite a bit of testing and doesn't get many foreign visitors. 

Perhaps so, but a better explanation for why the predictions of disaster haven't come to fruition in Belarus or Sweden lies in another BMJ article this week. It won't come as a surprise to 'armchair epidemiologists', but it's nice to see it in a major journal. 

The fact that only a minority of people, even in the hardest hit areas, display antibodies against SARS-CoV-2 has led most planners to assume the pandemic is far from over. In New York City, where just over a fifth of people surveyed had antibodies, the health department concluded that “as this remains below herd immunity thresholds, monitoring, testing, and contact tracing remain essential public health strategies.” “Whatever that number is, we’re nowhere near close to it,” said WHO’s Ryan in late July, referring to the herd immunity threshold.

But memory T cells are known for their ability to affect the clinical severity and susceptibility to future infection, and the T cell studies documenting pre-existing reactivity to SARS-CoV-2 in 20-50% of people suggest that antibodies are not the full story.

“Maybe we were a little naive to take measurements such as serology testing to look at how many people were infected with the virus,” the Karolinska Institute immunologist Marcus Buggert told The BMJ. “Maybe there is more immunity out there.”

 

T-cells and immunity from previous viruses are surely the most plausible explanations for why COVID-19 has infected and killed only a fraction of the number of people predicted in countries that didn't lock down. I'm glad the BMJ is now taking this seriously. It's time for SAGE and the politicians to do likewise.





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