A study in Denmark and Norway has found slightly increased rates of vein blood clots among people who have had a first dose of AstraZeneca’s COVID-19 vaccine, including clots in the brain, compared with expected rates in the general population. Researchers who conducted the study stressed, however, that such side effects are extremely rare, and the benefits of the vaccine still outweigh the risks in most situations. “The absolute risks of venous thromboembolic events described in this study are small, and the findings should be interpreted in the context of the benefits of COVID-19 vaccination at both the societal and the individual level,” they wrote in a summary of their findings published in the BMJ medical journal on Thursday. Norway suspended its rollout of the AstraZeneca vaccine on March 11 after a small number of cases of blood clots combined with bleeding and low platelet counts. Denmark has also withdrawn …