In this Motley Fool Live video recorded on March 26, healthcare and cannabis bureau chief Corinne Cardina and Fool.com contributor Adria Cimino discuss AstraZeneca's (AZN 0.84%) phase 3 trial data -- and why a U.S. health agency asked the company to reexamine its initial report.

Corinne Cardina: There's been a lot of headlines in the past week. Talking about the data that AstraZeneca used in its vaccine trial. Why is the U.S. asking questions about its latest trial information?

Adria Cimino: Well, an independent board monitoring the trial alerted the National Institute of Allergy and Infectious Diseases with a concern, and that was some of the data they thought was outdated. Dr. Fauci told STAT News that the reasoning behind this was that the press release results looked a little bit better than results from the latest data from the study, but he said it looked like an "unforced error." That was the problem that they had earlier in the week.

Cardina: Right. What should investors know about its vaccine efficacy that was reported this week?

Cimino: OK. Well, basically, that unforced error, that problem they had, it just had to do with the number of cases counted when they basically stopped and said, "OK, we're going to report." Earlier this week, they looked at 141 cases of COVID and found 79% efficacy. They updated to say, ''Now we looked at a 190 cases, we have 76% efficacy against symptomatic COVID." They have a 100% efficacy against severe disease -- that remained the same. Also, what was actually better was efficacy in the 65-plus age group was 85%, rather than 80%, which was previously announced. Eight cases of severe COVID all in the placebo group, and this is in a trial that involved more than 32,000 participants. Some pretty strong data there.