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

There is a need for better understanding of the risk of thrombocytopenic, haemorrhagic, thromboembolic disorders following first, second and booster vaccination doses and testing positive for SARS-CoV-2. Self-controlled cases series analysis of 2.1 million linked patient records in Wales between 7th December 2020 and 31st December 2021. Outcomes were the first diagnosis of thrombocytopenic, haemorrhagic and thromboembolic events in primary or secondary care datasets, exposure was defined as 0-28 days post-vaccination or a positive reverse transcription polymerase chain reaction test for SARS-CoV-2. 36,136 individuals experienced either a thrombocytopenic, haemorrhagic or thromboembolic event during the study period. Relative to baseline, our observations show greater risk of outcomes in the periods post-first dose of BNT162b2 for haemorrhagic (IRR 1.47, 95%CI: 1.04-2.08) and idiopathic thrombocytopenic purpura (IRR 2.80, 95%CI: 1.21-6.49) events; post-second dose of ChAdOx1 for arterial thrombosis (IRR 1.14, 95%CI: 1.01-1.29); post-booster greater risk of venous thromboembolic (VTE) (IRR-Moderna 3.62, 95%CI: 0.99-13.17) (IRR-BNT162b2 1.39, 95%CI: 1.04-1.87) and arterial thrombosis (IRR-Moderna 3.14, 95%CI: 1.14-8.64) (IRR-BNT162b2 1.34, 95%CI: 1.15-1.58). Similarly, post SARS-CoV-2 infection the risk was increased for haemorrhagic (IRR 1.49, 95%CI: 1.15-1.92), VTE (IRR 5.63, 95%CI: 4.91, 6.4), arterial thrombosis (IRR 2.46, 95%CI: 2.22-2.71). We found that there was a measurable risk of thrombocytopenic, haemorrhagic, thromboembolic events after COVID-19 vaccination and infection.

Automated summary

This study aimed to investigate the risk of thrombocytopenic, haemorrhagic, and thromboembolic events following COVID-19 vaccination and infection. The results showed an increased risk of haemorrhagic and idiopathic thrombocytopenic purpura events after the first dose of BNT162b2; a higher risk of arterial thrombosis after the second dose of ChAdOx1; a greater risk of venous thromboembolic events and arterial thrombosis after booster doses. In addition, there was an increased risk of haemorrhagic events, venous thromboembolic events, and arterial thrombosis post SARS-CoV-2 infection.