The commonest call I am receiving to my radio programs and also the commonest email enquiries are all around the clotting risk of the AstraZeneca vaccine for COVID-19. Firstly, let me make the general point about vaccination that it is a medical fact and not just an opinion that vaccination was the greatest advance of the 20th century.
Vaccinations have stopped millions of children dying from very nasty infectious diseases. Also, with conditions such as Polio, vaccines have stopped lifelong disability. For reasons not based on any science whatsoever but from occasional anecdotes, there has been a small but very noisy anti-vaxxing community continuing to spread gross misinformation based on no science whatsoever.
A number of years ago a medical researcher, Andrew Wakefield published falsified reports suggesting a link between the measles, mumps, rubella vaccination and autism. This has been completely disproven and has been shown to be fabricated evidence. But, still people believe this nonsense.
There have been a relatively small number of cases of clotting associated with the AstraZeneca vaccine throughout the world. This involves a very rare and specific antibody response where antibodies are produced to a particular platelet receptor known as platelet factor 4. If you are one of the very rare, unfortunate people to develop this condition, your platelet count drops markedly (a condition known as thrombocytopenia) and the platelets get extremely sticky leading to clotting. To date the estimated occurrence of this is somewhere between 1 in 100,000 people to up to 1 in 250,000 people.
Tragically, the amount of media time this is consuming is ridiculous. There had been an occasional death before this condition was well-recognised but now people being detected early, treated and coming to no harm.
To put this in perspective, the real harm is from developing COVID-19. To repeat the often-stated statistics, 20% of people who develop COVID-19 will develop the more severe form of the condition which may lead to serious lung problems often requiring a ventilator and 30% of these people with severe COVID will develop severe clotting abnormalities. Between 1–3 out of these 20 will possibly die especially if they are older or have serious comorbid conditions.
Recent reports have also suggested that a third of the patients who developed the more severe version of COVID-19 will develop long COVID characterised by fatigue, shortness of breath and cognitive problems. One study from Oxford University published in Lancet Psychiatry demonstrated that one third of COVID-19 survivors were diagnosed with significant neurologic or mental health disorders within 6 months of recovering from the acute condition.
Another study recently published in the journal “Nature” from the Washington School of Medicine in St Louis showed that even with mild cases of COVID, within 6 months of recovering, the risk of death from other conditions increased by 60%. Another study published in the World Journal of Men’s Health examined the potential for COVID to be associated with erectile dysfunction & infertility.
Back to the vaccinations, a recent study showed that in people over the age of 50, the AstraZeneca vaccine induces a better T-cell response (important for long-term memory and immunity) than the mRNA vaccines such as Pfizer or Moderna.
A prior history of clotting for other reasons does not increase your risk of clotting with the AstraZeneca vaccine as this is a very rare, specific antibody condition that has nothing to do with a prior clotting history. The only exception is if a person has experienced heparin induced thrombocytopenia syndrome which is very similar to the AstraZeneca induced thrombocytopenia syndrome. Heparin is a commonly used blood thinner given intravenously or subcutaneously in hospital to prevent clotting but paradoxically, around 1–3% of people who are given heparin develop this condition i.e. much more common than the AstraZeneca induced version.
Again, if you are on blood thinners, there is absolutely no reason why you should not receive the AstraZeneca vaccine if you over the age of 50. It is my opinion that the advice of the government for people below the age of 50 to receive the Pfizer vaccine is overcautious but still a reasonable suggestion as it appears that the rare AstraZeneca clotting reaction is more common in people below the age of 50.
My wife and I both had the AstraZeneca Covid vaccine last Saturday and fortunately had absolutely no reaction to this such as the typical fever, fatigue or a headache. I look forward to my second vaccination in 3 months’ time and hopefully by that stage there will be some sense in the discussion of allowing those of us who are vaccinated to recommence some form of international travel over and above the welcome travel bubble between here and New Zealand.
I know I will never convince the anti-vaxxers but to those of you are vaccine hesitant, I make a plea to trust the science. I have read extensively all of the literature on COVID-19 and the subsequent vaccinations around this condition and am convinced the only way we can stop this terrible pandemic that is still devastating many countries, is for as many people as possible around the globe to be vaccinated.