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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

Linked Editorial

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

if there is anything I can conclude from this study, it is the alarming observation that vaccinated people are at much higher risk of experiencing thrombotic events than unvaccinated people.

This conclusion is based on the fact that all participants in this study were vaccinated, including the ones that were tested positive for Covid. - Therefore, all reported cases of thrombotic events in the study occurred after vaccination.

The study claims to provide a comparison of the risk for severe complications for those being vaccinated against Covid and those being tested positive for Covid. However, for a valid comparison between those two groups the Covid control group would have to be unvaccinated.

Competing interests: No competing interests

29 August 2021
Julia Hermann
Manager
Switzerland