[Extract]
All vaccines can have rare adverse events, but during the pandemic, the report of isolated cases of blood clots associated to two of the anti-COVID vaccines that use adenovirus as a viral vector (AZD1222 and Johnson & Johnson) have raised concerns in the population, as well as emergency reviews, safety signals, and vaccination pauses. According to several reports, thrombosis associated to the AZD1222 vaccine occurred mainly in women under 55 years of age. Some governments of high-income countries that have more than one vaccine type available, like the United Kingdom and Canada, have instructed to administer AZD1222 according to specific age groups of apparent less risk. Others, like Denmark, stopped the use of that vaccine indefinitely...