A study of 5.4 million Scottish adults has revealed a small increased risk of an autoimmune bleeding disorder after the first dose of the AstraZeneca/Oxford COVID-19 vaccine, although a causal link hasn't been established.The study, led by University of Edinburgh researchers and published today in Nature Medicine, assessed the risk of bleeding-related events among 2.53 million people (57.5% of the population of Scotland 18 and older) up to 27 days after the first dose of the AstraZeneca or Pfizer/BioNTech vaccine from December 2020 to April 2021.Of the 2.53 million, more than 1.7 million received the AstraZeneca vaccine, while about 800,000 received the Pfizer version.The risk of the autoimmune bleeding disorder, immune thrombocytopenic