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Research

Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study

BMJ 2021; 374 doi: https://doi.org/10.1136/bmj.n1931 (Published 27 August 2021) Cite this as: BMJ 2021;374:n1931

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Strengthening international surveillance of vaccine safety

Rapid Response:

Re: Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study

Dear Editor

The risks of thrombocytopenia, venous thromboembolism, and arterial thrombosis as characterized in Table 2, even though broken down by vaccine and positive SARS-CoV-2 test - are all vaccinated populations, according to your study.

Therefore this is the rate of thrombotic events in a vaccinated population who has a "breakthrough" infection.

To my knowledge we do not know the prevalence of blood clots or venous thromboembolism in a vaccine naive population who test positive for SARS-CoV-2, most existing research examine hospitalizations and fail to take into account all infections, including asymptomatic and mild infections.

Please examine this higher risk for blood clots associated with breakthrough infection as this may be a safety signal.

Competing interests: No competing interests

29 August 2021
Courtney Oquist
Independent Researcher
California