COVID vs Clots

11th April 2021

UK COVID Deaths – Daily 7 / 7-Day average 36

Total UK COVID Deaths within 28 days – 127,087

Total UK Deaths with COVID-19 on the death certificate – 149,968 (up to 26 Mar)

James Cook Hospital – Total COVID deaths – 611

All COVID cases within South Tees Hospitals Trust – 23

James Cook Critical Care

COVID cases – 6 (6 ventilated)

Non-COVID cases – 50 (25 ventilated)

It’s taken the sad death of Prince Philip to unseat the pandemic from pole position in the nation’s newsfeeds. Prior to Friday though, the news had been packed full of stories about vaccine side-effects and the individual risks and benefits of vaccination.

In the UK there have been 79 cases of blood clots occurring in combination with low platelet counts in people who have received the Astra-Zeneca vaccine. All of the blood clots occurred after the first dose and 19 people have died as a result. The clots occurred in 51 women and 28 men, aged between 18 and 79 years. Platelets are present in your blood and normally help your blood to clot. The fact that the platelet count was low implies that an immune response was responsible, suggesting a complicated causal link between the clots and the vaccine.

By the end of March, over 31 million people had been vaccinated within the United Kingdom. Over 20 million doses of the Astra Zeneca vaccine had been used. These figures are astounding and, to be honest, I am surprised that we haven’t seen reports of significant side-effects before now. Every medical treatment or procedure carries the risk of adverse effects and vaccines are no exception. Obviously, any risk of harm must be weighed up against any potential benefit and it is reassuring to see that the announcement of the link between the Astra-Zeneca vaccine and blood clots has not been met with the usual hysteria. Any report of significant vaccine side-effects could easily derail any vaccination programme if not handled sensitively. Fortunately, it seems that, for once, media organisations are aware of the harm that could be done if some perspective is not included.

These blood clots have occurred in those receiving the AstraZeneca vaccine at a rate of about one in 250,000. Blood clots occur in 1 in 1000 women each year who take the oral contraceptive pill. Of course, this is not a direct comparison as women take the contraceptive pill every day rather than just once like a vaccine but it does help to quantify the risk somewhat. It may also help if we remember that 1 in 250,000 is apparently the risk of your home being hit by a crashing aeroplane. This is a rather old statistic and presumably, the risk is a lot lower at the moment, given the global reduction in air travel. However, I suspect that in more normal times, even those living close to an airport tend not to lose too much sleep worrying about it.

Of course, how we perceive risk is very subjective. The risk of actually dying from a vaccine-related blood clot seems to be in the order of 1 in a million. This is similar to your risk of being killed by a cow. Now, I have seen a couple of people killed by cows during my time in ICU and so, as a result, I personally would worry much more about death-by-Daisy than I would about dying following vaccination. Of course, there are many ‘dangerous’ things we all do that are worth worrying about such as driving, bouncing on trampolines, texting whilst crossing the road, getting drunk and eating too much pizza. Ultimately though, we all tend to ignore risk if it gets in the way of fun or convenience.

As a result of a careful risk vs benefit analysis, the decision has been made to offer an alternative vaccine (such as the Pfizer one) to all those under 30 years of age. At the moment, if you are over 30, the risks of serious illness (including blood clots) and death from COVID outweigh the risk of developing a vaccine-related blood clot. Of course, we will have to wait and see what effect this news has on vaccination uptake in the younger population but at least the argument for vaccination is still being presented rationally.

Blood clots notwithstanding, the benefit of vaccination continues to be demonstrated by the fall in COVID hospital admissions and deaths. Recent data suggests that the Pfizer vaccine still remains remarkably effective against the UK variant, even at six months after a second dose. It also appears effective against the South African variant despite laboratory studies that show a reduced level of antibody production. The same is probably true of its efficacy against the Brazil variant.

Certainly things are a lot better for us. There have been a number of days over the past week when we have not admitted a single COVID patient to the hospital. We have only ventilated two COVID patients over the past fortnight. One of these is too young to have been offered vaccination and the other became unwell a fortnight after being vaccinated. Unfortunately, you do need to wait at least three weeks after your first dose before being able to rely on any real degree of protection and I would strongly recommend that everyone waits until a fortnight after they have received their second dose before they alter their behaviour. There is, of course, an argument that we should all continue to be just as careful as we were prior to vaccination but I’m not naïve enough to believe that this is realistic.

The pubs open tomorrow and can serve food and drink outdoors. On a personal level, I’m pleased as I’ve missed them and I do need to stop drinking at home. Tomorrow will doubtless bring news footage of Boris enjoying a pint in some pub garden to prove that he is down with the electorate. Whilst I’m far from his biggest fan, I still believe that his timetable for relaxing restrictions is appropriate. It’s rather Goldilocks in my opinion; not too fast, not too slow – just right. We can’t throw caution to the wind just yet but we shouldn’t feel guilty about visiting a beer garden and toasting the nation’s vaccination success.