Blood clots and bleeding events following BNT162b2 and ChAdOx1 nCoV-19 vaccine: An analysis of European data

Abstract

The involvement of viruses and SARS-CoV-2 in autoimmune diseases is well known. The recent demonstration that ChAdOx1 nCoV-19 Covid-19 (AstraZeneca) vaccine (ChA) favors the production of anti-platelet factor 4 (anti-PF4) antibodies, blood clots, and thrombocytopenia raises the question of whether other anti-CoViD-19 vaccines favor the same patterns of events. We assessed the frequency of severe adverse events (SAEs) documented in the EudraVigilance European database up to April 16, 2021 related to thrombocytopenia, bleeding, and blood clots in recipients of ChA compared to that of recipients of the BNT162b2 Covid-19 (Pfizer/BioNTech) vaccine (BNT). ChA administration was associated with a much higher frequency of SAEs in each AE Reaction Group as compared with that elicited by BNT. When considering AEs caused by thrombocytopenia, bleeding and blood clots, we observed 33 and 151 SAEs/1 million doses in BNT and ChA recipients, respectively. When considering patients with AEs related to cerebral/splanchnic venous thrombosis, and/or thrombocytopenia, we documented 4 and 30 SAEs and 0.4 and 4.8 deaths/1 million doses for BNT and ChA recipients, respectively. The highest risk following ChA vaccination is in young people and, likely, women of reproductive age, as suggested by hypothesized scenarios. In conclusion, the immune reaction promoted by ChA vaccine may lead to not only thrombocytopenia and cerebral/splanchnic venous thrombosis but also other thrombotic and thromboembolic SAEs. These events are not favored by BNT vaccine. Our study may help in the evaluation of the benefit/risk profile of the ChA vaccine considering the epidemic curve present in a country.

Predictors of poor seroconversion and adverse events to SARS-CoV-2 mRNA BNT162b2 vaccine in cancer patients on active treatment

“…Moreover, there is insufficient data on seroconversion under targeted therapies as well as under hormone therapy for breast and prostate cancer patients which is generally deemed not to be immunosuppressive [ 14 ]. Similar uncertainties remain for the rate of adverse events following immunization (AEFI) in this frail population, particularly in light of the risk of hemorrhagic events in young females in the general population [ 15 ].…”

Symptomatic peduncular, cavernous bleeding following SARS-CoV-2 vaccination induced immune thrombocytopenia

“…Bleeding has been repeatedly reported as a complication of SARS-CoV-2 vaccinations 3 . The EudraVigilance European database listed 33 respectively 151 serious adverse events (SAE) with regard to ITP bleeding per one million doses in the BNT162b2 vaccine 4 . The number of SAEs related to cerebral or splanchnic venous thrombosis or ITP amounted to 4 SAEs and 0.4 deaths/1 million doses of the BNT162b2 vaccine 4 .…”

“…The EudraVigilance European database listed 33 respectively 151 serious adverse events (SAE) with regard to ITP bleeding per one million doses in the BNT162b2 vaccine 4 . The number of SAEs related to cerebral or splanchnic venous thrombosis or ITP amounted to 4 SAEs and 0.4 deaths/1 million doses of the BNT162b2 vaccine 4 . The pathophysiology background of bleeding after SARS-CoV-vaccinations is poorly understood but it is speculated that antibodies directed against thrombocyte surface proteins may impair their function why they are progressively removed from the blood.…”

Disproportionality analysis of adverse neurological and psychiatric reactions with the ChAdOx1 (Oxford-AstraZeneca) and BNT162b2 (Pfizer-BioNTech) COVID-19 vaccines in the United Kingdom

“…These findings coincide with those of Cari and colleagues, who compared the rate of events of thrombocytopenia, bleeding, and blood clots after ChAdOx1 or BNT162b2 in the EudraVigilance European database up to April 16, 2021. [18] Adverse reactions caused by thrombocytopenia, bleeding and blood clots were observed in 33 and 151 reports per 1 million doses of BNT162b2 and ChAdOx1, respectively. Cerebral and splanchnic venous thrombosis were also more frequent with ChAdOx1.…”