AstraZeneca vaccine has been approved for use in more than 50 countries, but not yet in the USA. The using of the AstraZeneca vaccine which developed with Oxford University was recently suspended in at least 22 countries for blood clotting reasons. After the statement on AstraZeneca COVID-19 vaccine safety of WHO, countries begin to reuse of AstraZeneca’s vaccine. The findings of a large U.S. trial showed, AstraZeneca vaccine is 79% effective in preventing symptomatic illness and and 100% effective against severe disease and hospitalization.