Thrombosis cases are more frequent after receiving the first dose of the coronavirus vaccine from the AstraZeneca laboratory than with that of Pfizer/BioNTech, although cases are very rare, according to a study published this Monday.
“After a first dose (of AstraZeneca vaccine) there is a 30% increased risk of thrombocytopenia compared to a first dose (of Pfizer/BioNTech vaccine)”points out the large-scale study published by the British Medical Journal (BMJ), according to the AFP news agency.
Thrombocytopenia is a form of thrombosis, that is, the formation of a blood clot with life-threatening consequences.
After the launch of vaccination campaigns against the coronavirus since 2021, a link between vial vector vaccines -AstraZeneca and Johnson & Johnson- and the appearance of these blood disorders was quickly suspected..
The study, carried out using health data from millions of patients in several countries in Europe and the United States, confirms that these thromboses are more frequent after the AstraZeneca vaccine, although they are very rare: 862 cases per more than one million vaccinated.
The risk appears to increase after the first dose. After the second, there is no difference between the AstraZeneca and Pfizer/BioNTech vaccines, adds AFP.
As for the Johnson & Johnson vaccine, the data points to an increased risk, but not clearly enough for researchers to draw a conclusion, according to the study.
The study comes above all to confirm “that all vaccines (anticovid) are safe and effective”, microbiologist Sarah Pitt told AFP, highlighting the “extremely rare” frequency of cases of thrombocytopenia.
