The US hasn't authorized AstraZeneca's vaccine for 2 main reasons. That could change in April.

French Health Minister Olivier Veran receives the AstraZeneca-Oxford COVID-19 vaccine on February 8, 2021.
THOMAS SAMSON/AFP via Getty Images
The US hasn't authorized AstraZeneca's vaccine because its trial is still going.Vaccine experts have also questioned inconsistencies in the company's global studies.
AstraZeneca's US trial results will likely clear up confusion in April.
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After more than a dozen countries paused the use of AstraZeneca's coronavi