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Late-Stage Covid-19 Vaccine Trial Underway in U.S.

Covid-19 vaccine infographic

Oxford Covid-19 vaccine infographic. Click on image for full-size view. (Oxford Vaccine Group, Univ. of Oxford)

1 Sept. 2020. Global drug maker AstraZeneca is starting its late-stage Covid-19 vaccine clinical trial in the U.S., with a vow not to cut corners in its processes. The company’s CEO issued an additional statement about its science-based principles in an apparent response to comments by Food and Drug Administration commissioner Stephen Hahn that the agency may authorize a Covid-19 vaccine before late-stage trials were completed.

The clinical trial is enrolling 30,000 U.S. adults at 62 sites to test AstraZeneca’s vaccine. The study team is enrolling healthy individuals, but still at risk of infection from SARS-CoV-2 viruses, randomly assigned to receive two doses of the vaccine, four weeks apart, or a placebo.

The vaccine is based on a technology developed at University of Oxford in the U.K. The technology, called ChAdOx1, uses a formula derived from an adenovirus in chimpanzees, similar to a virus in humans considered benign, or responsible at most for symptoms like the common cold. In this case, the adenovirus is genetically engineered to keep from replicating in humans, with genetic material added to make proteins similar to the characteristic spike glycoprotein on the surface of SARS-CoV-2 viruses. That spike protein binds to receptors in human cells, to gain entry and cause Covid-19 infections.

As reported by Science & Enterprise in July, early- and mid-stage trial results from 1,100 adults in the U.K. show the Covid-19 vaccine invokes two types of immune responses without serious adverse effects. That study tested the vaccine against a standard MenACWY vaccine approved to prevent against meningococcal infections that can lead to meningitis. The MenACWY vaccine was given for comparison instead of the usual saline solution to better gauge reactions to the Covid-19 vaccine, instead of adverse reactions to vaccines in general.

Results show after 14 days, vaccine recipients increased their volume of spike-specific T-cells by a median of 856 per million blood cells. These T-cells bind on and attack the invading viruses. And after 28 days, Covid-19 vaccine recipients also produced neutralizing immunoglobulin G, or IgG antibodies, in 91 percent of single-dose recipients and all of the double-dose — first and booster injection — recipients. While recipients generally tolerated the Covid-19 vaccine, many vaccine recipients reported mild and transient reactions including chills, fever, headache, and muscle pain.

On Sunday, FDA commissioner Stephen Hahn told the Financial Times (paid subscription required) that the agency would consider issuing an emergency use authorization, or EUA, for a Covid-19 vaccine before completion of late-stage trials, if supported by the data. Those reports generated harsh criticism in industry newsletters and on social media. FDA’s handling last week of an EUA for convalescent plasma to treat Covid-19 infections, generated similar criticism of knuckling under to political pressure, and already resulted in removal of the agency’s spokesperson.

In an apparent response to these reports, AstraZeneca issued a separate statement last night reiterating its commitment to “adhere to the highest scientific and clinical standards, making the safety and efficacy of the vaccine of paramount importance.” Company CEO Pascal Soriot says in the statement …

In recent weeks we have seen an increasing number of questions around the safety and availability of vaccines to fight this terrible Covid-19 pandemic and I want to reiterate my commitment that we are putting science and the interest of society at the heart of our work. We are moving quickly but without cutting corners, and regulators have clear and stringent efficacy and safety standards for the approval of any new medicine, and that includes this potential Covid-19 vaccine. We will remain true to our values as we continue our efforts to bring this vaccine broadly and equitably to billions of people around world.

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