In this pandemic, if you want avoid extra blood-clot risks, giving the jab a miss is not enough: you also have to dodge the virus

Take home message: 

If blood clots worry you, pay attention to the SARS-CoV2 coronavirus

There is a lot of confusion in Australia at the moment about whether to take the Astra Zeneca COVID-19 vaccine of not.

This decision needs to factor in likely future epidemic scenarios and is a complex personal decision. Careful scepticism about taking a vaccine offer is completely understandable, and indeed sensible if there is plenty of time available to make this decision. 

But we live in rapidly changing times, whether we like it or not.

A key aspect most people need think about when trying to make a vaccination decision is their personal risk of being infected with the COVID-19 virus during these rapidly changing times. Increasingly, with the emergence of new variants such as Delta, it is likely most people everywhere are now facing a tangible risk of coronavirus infection.

In this unfolding scenario, any risks from vaccination need to be compared to risks of infection. 

A very recent-- not yet peer reviewed -- article from respected medical scientists sheds light of these risks.

Here is the cover page

It's about blot clots in vaccinated and unvaccinated people, and provides counts for different kinds of adverse blood clotting events in Spanish (Catalonian)  people in those medical treatment categories during the COVID-19 epidemic.

These medical scientists detected a (low) signal of rare blood clot problems with both the Astra-Zeneca vaccine AND the Pfizer vaccine.

BUT.

They detected a much larger signal in people who became infected. 

Their summary statement at the end of the article:

They present a lot of detail about this, with most of it extremely interesting and relevant to vaccine decisions. A sample is given below of one graph in the article:

The blue symbols are results for people taking the Pfizer mRNA vaccine. The red are Astra-Zeneca vaccine first dose people. Orange are for people infected with COVID-19 virus. "Expected results' mentioned in the graphic are calculated numbers for the examined groups based on previous detailed medical studies of the normal Spanish population. These expected values make allowance for age and other demographic differences in the different groups that affect the background likelihood of blood clot problems being evaluated. 

Perhaps the most important points can be most easily seen from the last column of the graphic which summarises a measure of risk (they call it SIR for standardised incidence ratio which gives a fair measure of relative numbers of events occurring in vaccinated or infected groups compared to the overall unaffected human population). 

High SIR is bad, SIR near 1.00 is nothing happening.

SIR is much worse for every type of medical event for the COVID-19 (orange) diagnosed infected people than for people who accepted immunisation with either vaccine type. Unimmunised people are several-fold worse off than vaccinated people.

If blood clots worry you, pay attention to the SARS-CoV2 coronavirus

Study Citation

Burn, Edward and Roel, Elena and Pistillo, Andrea and Fernandez-Bertolín, Sergio and Aragón, Maria and Reyes, Carlen and Verhamme, Katia and Rijnbeek, Peter and Li, Xintong and Strauss, Victoria and Prieto-Alhambra, Daniel and Duarte-Salles, Talita, Thromboembolic Events and Thrombosis With Thrombocytopenia After COVID-19 Infection and Vaccination in Catalonia, Spain. Available at SSRN: https://ssrn.com/abstract=3886421 or http://dx.doi.org/10.2139/ssrn.3886421

See also 

Collected COVID-19 risk yardsticks