Risk of thrombocytopenia and thrombocytopenia after covid-19 vaccination and positive SARS-CoV-2 test: a self-management case series study
BMJ 2021; 374: n1931
Commentary
This study was designed to evaluate the association between covid-19 vaccine and the risk of thrombocytopenia and platelet embolism after infection in adults.
Setting patient-level data were obtained for approximately 30 million people vaccinated in the UK between December 1, 2020 and April 24, 2021.
29,121,633 people were initially vaccinated, 19,608,008 with AstraZeneca (ChAdOx1 nCoV-19) and 9,513,625 with Pfizer-BioNTech (BNT162b2 mRNA)), and 1,758,095 people tested positive for SARS-CoV-2.
Outcomes analyzed included hospitalization or death related to thrombocytopenia, venous thromboembolism, or arterial thromboembolism within 28 days of three exposures.
Results showed
that there was an increased risk of thrombocytopenia after ChAdOx1 nCoV-19 vaccination (incidence rate ratio 1.33, 95% confidence interval 1.19-1.47, 8-14 days) positive SARS-CoV-2 test (5.27, 4.34-6.40, 8).
There was also an increased risk of venous thromboembolism after ChAdOx1 nCoV-19 vaccination (1.10, 1.02 to 1.18 in 8-14 days) and SARS-CoV-2 infection (13.86, 12.76 to 15.05 in 8-14 days) and after BNT162b2 mRNA vaccination (1. 06, from 1.01 to 1.10) and increased risk of arterial thromboembolism after SARS-CoV-2 infection (2.02, from 1.82 to 2.24 in 15-21 days).
Secondary analysis showed an increased risk of CVST after ChAdOx1 nCoV-19 vaccination (4.01, 2.08 to 7.71 in 8-14 days), after BNT162b2 mRNA vaccination (3.58, 1.39 to 9.27 in 15-21 days), and after positive SARS-CoV .
After BNT162b2 mRNA vaccination (1.12, 1.04 to 1.20 in 15-21 days), increased risk of ischemic stroke after positive SARS-CoV-2 test; after ChAdOx1 nCoV-19 vaccination (1.21, 1.02 to 1.43 in 8-14 days), increased risk of ischemic stroke after positive SARS-CoV-2 test After positive test, there was an increased risk of other rare arterial thrombotic events.
These results suggest
that an increased risk of hematological events requiring hospitalization or leading to death after the first dose of the vaccine was observed over a short time interval.
However, the risk of these events was found to be substantially higher and longer lasting after SARS-CoV-2 infection than after vaccination in the same population.
