Thromboembolic events and hemorrhagic stroke after mRNA (BNT162b2) and inactivated (CoronaVac) covid-19 vaccination: A self-controlled case series study

Risk for Myocardial Infarction, Stroke, and Pulmonary Embolism Following COVID-19 Vaccines in Adults Younger Than 75 Years in France

“…For hemorrhagic events 0 to 27 days after vaccination, the adjusted RR was 1.48 (CI, 1.12 to 1.96), with an SCCS RR of 0.95 (CI, 0.82 to 1.11). Finally, a recent study in Hong Kong detected a possible safety signal for hemorrhagic stroke after receipt of the Pfizer–BioNTech vaccine ( 11 ); our study did not confirm this signal. To our knowledge, no study to date has assessed the association between the Janssen vaccine and risk for cardiovascular events.…”

A post-marketing safety assessment of COVID-19 mRNA vaccination for serious adverse outcomes using administrative claims data linked with vaccination registry in a city of Japan

“…These findings are consistent with the results of previous observational studies including a modified SCCS for BNT162B2 [13] , and cohort studies for BNT162B2 and both mRNA vaccines [5] , [6] . However, a recent modified SCCS using Hong Kong electric health and vaccine records suggested an increased risk of haemorrhagic stroke within 27 days after COVID-19 mRNA vaccination in the overall population (IRR; 1st dose: 1.67 [1.04–2.69]; 2nd dose: 1.68 [0.99–2.84]) [14] . A large comparative study would be needed to confirm such a risk; however, our analysis did not show any increased risk of these diseases.…”

“…Thus, we applied the “modified” SCCS, which can treat such outcome-dependent exposures [11] , [12] . Some previous studies evaluating the risk of COVID-19 vaccination on some serious outcomes also used the modified SCCS [13] , [14] . According to the recommendation in the methodological papers for modified SCCS [11] , [12] , we artificially prolonged the follow-up until the end of the study period (30th September 2021) if the follow-up of the participant ended due to death.…”

Risk of thrombocytopenic, haemorrhagic and thromboembolic disorders following COVID-19 vaccination and positive test: a self-controlled case series analysis in Wales

“…To our knowledge, this is one of the first studies on evidence of the adverse bleeding and clotting risks following first and second dose of ChAdOx1 or BNT162b2 vaccination and boosters including mRNA-1273. Various studies, including ones from Scotland, England and Denmark have reported associations of first vaccination dose with adverse bleeding and clotting events 12 – 14 , 28 , 29 ; however, none of the studies reported on risk post second dose and booster. Our results show that some risks persist post second and booster doses but there is considerable uncertainty due to the rarity of events.…”