Janebabe, are you involved with health care in any way? The way in which you understand risk and side effects sounds like it! 
What you have posted about the blood clot risk is something that I wish the average person in Australia would take the time to research properly. It is indeed a very minimal risk, and there are similar or higher risks in many medicines, other vaccines, etc.
@everyone... (Sorry, I am reading back and I KNOW it's a scroller.)
There are blood clot risks for people who take no medicine, for people who take some medicine, for people who take health supplements, for people who are physically active, for people who are genetically predisposed to certain conditions, for people who smoke, for people who don't smoke, for people who ... well, I could go on, but I'll try to keep it reasonably short!
Everything that we do carries with it risk. In terms of blood clots... Some are inherent, in our specific DNA. Some are a result of certain kinds of medication. Some are a result of lack of certain kinds of medication. Some are the result of certain kinds of activity. Some are the result of trauma. Some are the result of insufficient sleep. Some are the result of overwork. Some lie hidden for years and even after one's death, are unlikely to be listed on the autopsy report.
We live with risk every day of our lives. Often we barely quantify or acknowledge those risks. We ignore the risks of crossing the road, driving a car, getting onto an aeroplane. Most people are extremly half-hearted about the risks of the foods they eat, or don't eat; some will be very resistant to acknowledging the risks of cigarettes, alcohol, drugs. Many of us work for too many hours each week, hardly aware that this has severe and cumulative health risks. Our sporting activities carry inherent risks, but avoiding exercise altogether causes other risks.
The blood clot risks of a vaccine such as the AstraZeneca COVID-19 vaccine are significantly lower than the risks of a blood clot due to contracting COVID-19. That is something which the media has either ignored or played down, and that irresponsible reporting has muddied the waters and caused even intelligent people to come to unwarranted conclusions. A recent study Cerebral venous thrombosis and portal vein thrombosis : a retrospective cohort study of 537,913 COVI... is well worth reading. Its objectives: To estimate the absolute risk of cerebral venous thrombosis (CVT) and portal vein thrombosis (PVT) in the two weeks following a diagnosis of COVID-19, and to assess the relative risks (RR) compared to influenza or the administration of an mRNA vaccine against COVID-19.
The results: The incidence of CVT after COVID-19 diagnosis was 42.8 per million people (95% CI 28.5 – 64.2) including 35.3 per million (95% CI 22.6 – 55.2) first diagnoses. This was significantly higher than the CVT incidence in a matched cohort of patients with influenza (RR= 3.83, 95% CI 1.56 – 9.41, P<0.001) and people who received an mRNA vaccine (RR= 6.67, 95% CI 1.98 – 22.43, P<0.001). The incidence of PVT after COVID-19 diagnosis was 392.3 per million people (95% CI 342.8 – 448.9) including 175.0 per million (95% CI 143.0 – 214.1) first diagnoses. This was significantly higher than the PVT incidence in a matched cohort of patients with influenza (RR=1.39, 95% CI 1.06 – 1.83, P=0.02) and people who received an mRNA vaccine (RR=7.40, 95% CI 4.87 – 11.2, P<0.001). Mortality after CVT and PVT was 17.4 % and 19.9 % respectively.
Spoiler
❝In a large electronic health records network, the absolute incidence of CVT and PVT in the 14 days after COVID-19 diagnosis was 42.8 and 392.3 per million patients respectively. The incidence rapidly decreased in the following weeks, which is compatible with a causal link between COVID-19 and those thrombotic events. However, causation can not be demonstrated with the current study and residual confounding (e.g. increased medical monitoring directly after COVID-19 vs. a few weeks later) might contribute to this observation. The incidence of CVT and PVT after COVID-19 is substantially greater than in the matched control cohorts.
The incidence of CVT after a diagnosis of COVID-19 is also substantially greater than the expected incidence in the general population in the USA, estimated to be between 0.53 and 0.77 per million people in any 2-week period and the rate is significantly higher than the highest of these estimates (binomial test: P<0.001). The incidence is also many-fold higher than the latest reported incidence of CVT following administration of the first dose of the ChAdOx1 nCoV-19 (‘Oxford-AstraZeneca’) vaccine (reported by the European Medicines Agency to be around 5 per million vaccinated people) and the latest reported incidence of CVT following administration of the Ad26.COV2.S (“J&J”) vaccine (reported by the Food and Drug Administration to be about 0.9 per million vaccinated people).❞
| incidence of CVT in patients with COVID-19 | 42.8 per million |
| incidence of PVT in patients with COVID-19 | 392.3 per million |
| CVT incidence in general population (USA) | between .53 and .77 per million |
| incidence of CVT post-vaccination (Oxford-AstraZeneca) | 5 per million |
- This equates to the risk of developing a blood clot as a result of taking the AstraZeneca vaccination being 0.0005%.
- The risk of developing a blood clot as a result of contracting COVID-19 is 0.00428 % (CVT) and 0.03923% (PVT) respectively.
- A person is more than 8 times more likely to develop CVT, and more than 78 times more likely to develop PVT, as a result of contracting COVID-19 than as a result of having the AstraZeneca vaccine.
CVT/PVT is rare in the general population, but it is also rare post-AstraZeneca. We are talking about a risk that in any terms is very small indeed: less than 1%. Less than 0.1%. Less than 0.01%... Less than 0.001%.
Check the incidences of side-effects in any medicine that you're prescribed; you are very likely indeed to see most of the side effects with higher risks than 0.0005%. By any medical measure, that is a fantastically low risk, and leads to the statement "This vaccine is very well tolerated" being highly applicable and completely correct.
Why is there such hesitation as a result of this tiny percentage? ... Because - in my opinion - of the way that the media has reported it. Every single example of an affected person is reported, with alarmist terminology and a general tone of doomsday and blame.
For the record, I believe in full transparency. The incidence of any such reaction should be released but it must be released in context and without the sensationalist language used by journalists who should simply be reporting rather than trying to be medical experts - which they are not. Journalists are not releasing the incidences of every single COVID-19 patient with CVT/PVT. They're not releasing the incidences of every side effect (including ones with a moderate risk of a moribund outcome) in every medication, or as a result of every sickness, or as a result of people travelling or drinking certain things or eating certain foods. That would of course be absurd - but it does highlight just how much of a sideshow some of the vaccine reporting has become. It's irresponsible, misleading, illogical, ill-founded, non-specialist, and pandering to the lowest common denominator.
DISCLAIMER: In the interests of full transparency, I was given the unexpected opportunity to be vaccinated with AstraZeneca, and I have taken it without hesitation. It's been more than a month since that first dose, and if I suffered any side effects at all, it was fatigue. I cannot even say with certainty that the fatigue was linked to the vaccine, as there are many reasons why I might be/have been exhausted.
