A note on COVID vaccines and blood clots

Alan Taylor
3 min readApr 19, 2021

I decided to post an email I wrote (lightly edited) about my thoughts on the blood clotting controversy with certain COVID-19 vaccines. I may write a fuller post on this topic in future.

The question of whether to approve (COVID) vaccines which have side effects is tricky and ethically fraught.

Personally, I’m quite sympathetic to utilitarianism, so can sleep fairly easily with a vaccine that saves millions of lives being approved, even if it harms or kills a few dozen people.

I understand there are a lot of (good) reasons that regulatory bodies have a high level of caution over safety of drugs, which makes sense, but I think that exceptions can sometimes be made in emergencies (in much the same way that rules to everyday social norms can be broken in times of emergency, i.e. it is normally bad form to be late for a meeting but it is ok if you saw someone being attacked on the way and had to call the police). In pandemics, there is such urgency in saving lives that I think it may be reasonable to have less strict ‘safety’ regulations (I use inverted commas because it is of course, in many ways, unsafe to allow people to die from COVID while an effective vaccine is ready to be used).

The FDA pausing J & J distribution will cost thousands of lives, to save perhaps a handful. For me, this is not right.

There is then a somewhat separate question involving transparency, which I think is even more difficult and I don’t have a good answer to.

Transparency seems good in general, and I too feel uncomfortable to hear of ‘cover-ups’ over side effects of vaccines in previous pandemics. When these things come out, they erode public trust in health systems, and systems more broadly, which seems very bad.

So, I’m in favour of a high level of transparency, generally speaking.

However, with this particular case, it seems to me inevitable that the widespread reporting of blood clotting side effects from COVID vaccines was near-certain to erode trust in vaccines, both for COVID and in general. Because the reported risks from blood clots are so low, it is not clear to me that this is something the public really needs to be aware of.

People are bad at reasoning with risk; if you tell them the risk from blood clotting is 5 in a million, they won’t have a good sense of what that means, but if you report a headline ‘AZ vaccine found to cause blood clots’, you know for a 100%-sure-fire-thing that a lot of people are going to cancel their vaccination plans, no matter the risk.

So, it seems like this was a somewhat backwards endeavour. We promote transparency to promote trust, but reporting about these side-effects seems to have reduced, rather than increased, trust in public health. And, it wouldn’t even need to be a ‘cover up’… there is a lot of data on every aspect of COVID and not all of it is reported.

It is a choice what is reported and what isn’t, yet most parts of scientific papers left out of press reports are not seen as ‘cover ups’. For me, it’s not clear that reporting this data was in the public’s interest.

But, as I say, I’m less sure on this point.