Understanding Clinical Trials
AstraZeneca CEO admits an error in the first trial may have skewed results and will likely have to run a second global trial to assess its COVID-19 vaccine’s efficacy. The company admits that the most effective regimen results it has so far produced were an accident.
UK pharmaceutical company AstraZeneca, CEO told Bloomberg News it and the University of Oxford preliminary results released last Monday showed their two-dose vaccine could be up to 90% effective at preventing COVID-19. Later it discovered there was an error in the trial, leaving some participants with half-doses. Experts say that error casts doubt on the validity of the efficacy rate cited and warrants further study.
During the trial, the testing error admission has scientists and drug development experts quickly questioning their ‘trust in the validity of AstraZeneca’s COVID-19 vaccine data.
AstraZeneca and the University of Oxford initially reported Monday that their coronavirus vaccine was found to be up to 90% effective based on preliminary results from studies of 23,000 volunteers in Brazil and the UK. Those results helped rally US stock indexes. They now report an error during its initial trial, prompting a barrage of doubts and scores of questions.
According to Bloomberg News, the pharmaceutical company’s CEO, Pascal Soriot, acknowledged the concerns and said it would likely conduct a second trial of the two-dose vaccine.
AstraZeneca becomes the third company to report positive initial results from late-stage studies. Moderna and Pfizer said earlier this month that their vaccines were 94.5% and 95% effective.
AstraZeneca’s efficacy rate, however, was more complicated.
According to several sources, the dosing error during its trial resulted in about 2,700 participants receiving a half-strength dose followed by a full-strength dose. In that subgroup, the vaccine was 90% effective at preventing COVID-19, AstraZeneca said.
But in a group of about 9,000 participants who received two full-strength doses, that efficacy rate dropped to 62%. Dr. Fauci has said that just 50% efficiency would be acceptable in the worst-case scenario.
Some experts attempted to interpret this broad range in efficacy, but that turned sour when AstraZeneca announced that the most effective regimen was an accident.
Soriot told Bloomberg News….
“Now that we’ve found what looks like a better efficacy, we have to validate this, so we need to do an additional study,”
According to Soriot, the error meant about 2,700 participants got 1 1/2 vaccine doses instead of the intended two. That resulted in a higher efficacy rate than among those who got the prescribed amount.
Soriot told Bloomberg that to clarify this discrepancy and meet the public-health community’s demand for more data, AstraZeneca would likely run another “international study” to examine the strength of the half-dose/full-dose regimen among more participants.
“But this one could be faster because we know the efficacy is high, so we need a smaller number of patients,” he added.
Sheila Bird, a biostatistician from the University of Cambridge’s Medical Research Council, told Politico on Thursday that…
“This is a considerable complication” because the half-dose/full-dose regimen “occurred in error” and was not by design.
Moncef Slaoui, the head of the US’s Operation Warp Speed vaccine-development program, also pointed out that…
“The small group didn’t include any participants over the age of 55, which could explain why the vaccine was more effective at preventing COVID-19.”
Others see a much more notorious reason for the bad trial numbers and accuse AstraZeneca of “cherry-picking” data to make it seem like the vaccine had a higher efficacy rate. Wired reported on Wednesday that it was not transparent about its 70% average efficacy figure.
It’s equivalent that all three vaccine frontrunners are still considered experimental. None of the companies has published results in any legitimate medical journal. The Food and Drug Administration (FDA) has not authorized any emergency use shots, let alone give them full approval.
AstraZeneca Says It’s Likely to Run Fresh Global Vaccine Trial