Very small blood clot risk after first AstraZeneca COVID shot – UK studies

Cases of rare blood clotting emerged early last year as the rollout of the AstraZeneca-Oxford vaccine began in Europe.

Johnson & Johnson’s (JNJ.N) COVID-19 vaccine, which is based on a similar platform to the AstraZeneca-Oxford shot, has also been associated with the rare combination of blood clotting and low platelet counts. read more

Some countries have restricted or suspended use of the vaccines after the EU drug regulator confirmed possible links between the shots and the conditions. read more

International drug regulators have said the benefits of vaccines outweigh the risks. read more

The study is in line with a review by the EU drug regulator which said last month there were fewer such side effects observed after the second AstraZeneca dose. read more

AstraZeneca said in a statement the study confirmed what is already known about “extremely rare blood disorders following vaccination.”

“The risk of developing this very rare condition remains substantially higher after COVID-19,” it added.

Last year, a study led and funded by AstraZeneca found its vaccine carried a small additional risk of thrombosis with thrombocytopenia syndrome after the first dose but none after the second. read more

AstraZeneca-Oxford’s ChAdOx1 nCoV-19 shot, sold under the brands Vaxzevria and Covishield with more than 2.6 billion doses supplied globally as of February, remains a key weapon against the pandemic in middle-income countries.

A second peer-reviewed British study also released on Tuesday found the risk of cerebral venous sinus thrombosis (CVST) in the four weeks after receiving the AstraZeneca-Oxford shot was roughly twice as high as before vaccination, but it still implied only one in four million people could have the side-effect.

The study assessed data for more than 11 million people in England, Scotland and Wales, spanning nearly seven months from December 2020 to June 2021.

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