FACTBOX: How countries use vaccines
SOME countries are restricting the use of the AstraZeneca COVID-19 vaccine to certain age groups, or suspending use, after European and British regulators confirmed possible links to rare blood clots. Johnson & Johnson's single-shot vaccine has also been hit by concerns over blood clots. European regulators are reviewing such cases and are expected to issue findings on April 20. U.S. federal health agencies recommended pausing its use temporarily on April 13 and a U.S. health advisory panel will meet on April 23 to discuss whether the pause should continue. J&J has stated that no clear causal relationship has been established…