A statement describing the error came days after the company and the university described the shots as “highly effective” and made no mention of why some study participants didn't receive as much vaccine in the first of two shots as expected.
In a surprise, the group of volunteers that got a lower dose seemed to be much better protected than the volunteers who got two full doses. In the low-dose group,
The partial results announced Monday are from large ongoing studies in the
DID RESEARCHERS MEAN TO GIVE A HALF DOSE?
Before they begin their research, scientists spell out all the steps they are taking, and how they will analyze the results. Any deviation from that protocol can put the results in question.
In a statement Wednesday,
WHAT ABOUT THE RESULTS THEMSELVES?
Experts say the relatively small number of people in the low dose group makes it difficult to know if the effectiveness seen in the group is real or a statistical quirk. Some 2,741 people received a half dose of the vaccine followed by a full dose,
Another factor: none of the people in the low-dose group were over 55 years old. Younger people tend to mount a stronger immune response than older people, so it could be that the youth of the participants in the low-dose group is why it looked more effective, not the size of the dose.
Another point of confusion comes from a decision to pool results from two groups of participants who received different dosing levels to reach an average 70% effectiveness, said
“You’ve taken two studies for which different doses were used and come up with a composite that doesn’t represent either of the doses,? he said of the figure. “I think many people are having trouble with that.?
WHY WOULD A SMALLER FIRST DOSE BE MORE EFFECTIVE?
Oxford researchers say they aren’t certain and they are working to uncover the reason.
“It’s the Goldilocks amount that you want, I think, not too little and not too much. Too much could give you a poor quality response as well,’’ she said. “So you want just the right amount and it’s a bit hit and miss when you’re trying to go quickly to get that perfect first time.”
WHAT ARE THE NEXT STEPS?
Details of the trial results will be published in medical journals and provided to
“But we want it to be based on data and science,” he said.
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