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What Just Happened to the AstraZeneca Vaccine?

On Monday I thought I would be reviewing the Covid-19 US data from the Phase 3 Clinical Trial in preparation for the FDA request for an EUA.  It was one of the first vaccines I learned about.  Oxford University developed the platform for the Viral Vector vaccine using a Chimp adenovirus to carry the DNA for the SARS-CoV-2 spike protein into the cells - leading to spike protein production to stimulate the human immune response.  The vaccine was produced in concert with AstraZeneca, and was selected as part of Operation Warp Speed by the US.  For approval here vaccine makers had to conduct a Phase 3 Clinical Trial with at least 30,000 US volunteers - with a full range of ages, races, and ethnicity.  As soon as more than 50% of the volunteers were followed for side effects for more than 2 months, an application could be made to the FDA for EAU. 

Then I woke up Tuesday to several online news alerts: "AstraZeneca's US trial data may have been outdated and incomplete NIH says" (Washington Post). The Data and Safety Monitoring Board, is a group of 11 independent scientists appointed by NIH to oversee the clinical trials with each of the companies.  They suggested that AstraZeneca should include data on all of the volunteers that were beyond 2 months before publishing their efficacy data.  They didn't.  The DSMB has that data and when more volunteers were included, efficacy dropped.  It is highly unusual for the FDA/NIH to make an announcement like this and no further details were given in the first newspaper articles.  Read More Below


Later Tuesday afternoon this was the NYT Breaking News Headline, "In a two-page letter to AstraZeneca and federal authorities, an independent panel of medical experts that was helping to oversee the vaccine's clinical trial in the United States said that the company had essentially cherry-picked data that was most favorable for the study as opposed to the most recent and most complete."  This is a problem with transparency.

The main issue, as written in the news, is that the data up to February 17 was the final data used to determine an efficacy of 79%.  But when the advisory board included data collected after Feb 17, there were more Covid-19 patients diagnosed and they were in the vaccinated group thereby reducing efficacy to 69-74%.  AstraZeneca in their initial Phase 3 Clinical Trial in Europe used two dose regimens in an error, and those volunteers that received half of the planned dose had fewer cases of Covid-19 than the full dose volunteers.  That was difficult to explain and now there are more questions. 

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