What we know about AstraZeneca vaccine blood clot reports

German officials have decided to limit the use of AstraZeneca’s coronavirus vaccine in people under 60 after more unusual blood clots were reported in a small number of people who received the shots.

Earlier in March, more than a dozen countries, including Germany, suspended their use of AstraZeneca over the blood clot issue. Most restarted — some with the kinds of restrictions Germany imposed Tuesday — after the European Medicines Agency said the benefits of the vaccine outweighed the risks of not inoculating people against COVID-19. But the seesawing back and forth in some countries on who can take the vaccine has raised concerns that its credibility could be permanently damaged. Here's a look at what we know — and what we don't.