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There were other dosing issues as well that weren’t explained, although dosing is the centerpiece of the press release. There are many different treatment regimens in these trials – the UK study has more than two dozen arms, meaning the volunteers were divided into as many groups based on age and amount of vaccine given and from the moment. The doses are measured by the number of modified viral particles they contain, and the developers decided that the standard dose would be 5 x 1010 viral particles. But for many of these arms in the UK trial – as well as for anyone who received the vaccine in the Brazilian trial – publicly available information about the trial shows that the standard dose could be anywhere from 3, 5 and 6.5 × 1010 virus particles. The lower end of this range is not far from half a dose.
How did Oxford-AstraZeneca end up with this patched-up analysis instead of data from one big trial? After all, this vaccine went into phase 3 before the BNT-PFizer or Moderna. But in the UK, where these tests started, the Covid-19 epidemic has receded. This meant that the results would come very slowly.
A month later, a second phase 3 trial for the vaccine began in Brazil. This was aimed at healthcare workers, for whom the risk of being exposed to Covid was much higher than for people taking part in the trial in the UK. But the two trials had other substantial differences. In the UK, for example, volunteers who did not receive the experimental Covid vaccine received an injection of meningococcal vaccine; in Brazil, people in the control group were injected with saline as a placebo.
Meanwhile, BNT-Pfizer and Moderna began Phase 3 trials for their coronavirus vaccines on the same day in July: both planned to include 30,000 volunteers at the time, and both trial plans were FDA approved. Oxford-AstraZeneca then announced that they too would hold a trial of 30,000 people in the United States.
But this research on the Oxford-AstraZeneca vaccine quickly lagged behind others. The US trial was approved by the FDA, but it didn’t start recruiting people until the end of August; and just a week later it was put on hold so that the FDA could investigate a serious adverse event in the UK trial. The cause of the volunteer’s illness was unclear, but the FDA did not give the green light for the U.S. trial of Oxford-AstraZeneca to resume until October 23. At that time, the trial protocol had been made public. He says the plan is to inject the vaccine in two standard doses, one month apart; and two people will be vaccinated for each person who receives a placebo saline injection.
So here we are at the end of November. BNT-Pfizer and Moderna offered a master class on how to quickly conduct major vaccine trials in a pandemic, while Oxford-AstraZeneca has only an assortment of smaller trials ready at this time. to be considered.
But wait, no more red flags! Last week, Oxford-AstraZeneca published some earlier results in the development of the UK trial. This document included a test protocol for the UK study, attached as an annex. At the bottom of this paper, and seemingly overlooked by reporters and commentators, was one eyebrow-raising suggestion: Under a section titled “Intermediate and Primary Analyzes of Primary Outcome,” the researchers sketched out a plan for combining and analyzing data from four clinical trials (only half of which is phase 3), carried out in different ways on three different continents. The plan, they wrote, was to extract results only for people in those four trials who had obtained “two vaccines at standard dose,” and then pool them for what’s called a meta-analysis.
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