LOUISVILLE, Ky. — Three Mondays in a row brought new coronavirus vaccine development news. The latest update came when AstraZeneca, in partnership with Oxford, announced its COVID-19 vaccine is 70% effective on average. Amid that promising news, some United States experts have questioned the trial method.

“There is some controversy about this AstraZeneca vaccine because of a mistake that was made about the contract organization that in the beginning was guiding the testing of the vaccine,” University of Louisville School of Medicine Vice Dean for Research, Dr. Jon Klein, said.

The drug maker said two different regimens were used for the two dose vaccine. One group in Great Britain received a half dose the first time and a full does the second time resulting in 90% efficacy. Another group in Brazil received a full dose the first and second time, resulting in only 62% effectiveness.

"As the week went on, what they also realized was that the group in Great Britain was younger, so there are some questions as to whether the group in Great Britain had 90% efficacy because they are younger as opposed to the lower dose," Dr. Klein said.

Dr. Klein said more research is needed to sort out that discrepency. He said the big takeaway is that, no matter what the efficacy ends up being, the AstraZeneca vaccine works in some capacity. 

“If it’s just slightly less effective, if it’s 60 to 70 percent, it’s still going to get used. We are going to need all of these vaccines to vaccinate the some 8 billion people in the world,” Dr. Klein said.

The news from AstraZeneca follows coronavirus vaccine updates from Pfizer and Moderna, both of which are more effective than AstraZeneca's vaccine. Dr. Klein said, if AstraZeneca ends up being 60-70% effective, it would still exceed the bar set by the FDA and CDC. When vaccines are available, Dr. Klein said people will likely be urged to take whatever vaccine is available to them.