Possibility of the blood clot, thrombotic thrombocytopenia following injection of COVID-19-vaccine AstraZeneca; a systematic review

Introduction: Recently, it has been reported that the injection of vaccines such as the ChAdOx1 nCoV-19 (AstraZeneca) involves some rare cases of thrombocytopenia and blood clots, although the vaccines created immunity in people. Estimates of this phenomenon are not the same in different countries, probably due to age distribution and number. Objectives: This study attempted to study AstraZeneca’s rare side effects in people injected with this vaccine. Methods: This systematic study was conducted using articles published in 2021 under the title of blood clot and thrombocytopenia by AstraZeneca injection. The references and data were gathered through national and international sites such as Magiran, Google Scholar, PubMed, Web of Science, and Scopus. They were also gathered and examined using report cases and the available data on COVID-19 vaccine immunization in various countries. The keywords used mainly are COVID-19 vaccine, ChAdOx1 nCoV-19 vaccine, blood clots, thrombus, thrombotic, and thrombocytopenia. Eventually, 25 articles were searched and examined, of which 15 related ones were selected after reviewing and re-studying. While investigating the summary and method in those 15, they were filtered more accurately; finally, ten articles were chosen. Inclusion criteria consisted of all related articles and exclusion criteria contained articles that were less related to our research subject after purification or were redundant and not of high quality. Results: This study found that rare blood clot cases and thrombocytopenia were seen despite mild side effects after AstraZeneca injection. After assessing its benefits, adverse effects, and age distribution, the countries using AstraZeneca decided to continue using it. The main difference in reported statistics in these countries is due to the variety in the age and number of people receiving the vaccine. Conclusion: Blood clots and thrombocytopenia are among the rare side effects of the AstraZeneca vaccine. In different countries, the vaccine side effects vary depending on the age and number of participants. Anyway, according to the investigations conducted in this area, the highest records of these side effects are observed in Norway, which is still low. Overall, through studying this study and other similar ones, politicians, managers, and even ordinary people can be informed about the pros and cons of this vaccine.