COVID-19 vaccine trial halted after participant becomes seriously ill

ATLANTA - The drug giant AstraZeneca has temporarily shut down its coronavirus vaccine trial, after a British volunteer in the study became seriously ill.

A company spokesperson called the pause "routine," and said it is something that needs to happen anytime a participant in a clinical trial suffers an unexplained severe adverse reaction.

In Atlanta, Dr. Carlos del Rio, an infectious disease specialist at the Emory School of Medicine, believes the company made the right call.

"This is what clinical research is, and this is how you do it," Dr. del Rio told reporters. "You don't put participants at risk."

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AstraZeneca has not revealed what sort of medical complication the trial participant experienced.

Until more is known about this case, Dr. del Rio, whose hospital system is testing the Moderna mRNA vaccine, another leading COVID-19 vaccine candidate, says it makes sense for AstraZeneca to halt its research to investigate the issue.

"That's how clinical trials work, that is what clinical trials do," del Rio says.  "You are continually seeing if there are any issues, and, out of an abundance of caution, you put a hold when something serious happens, and you want to see what the issue was."

AstraZeneca began large-scale phase 3 clinical trials in the US in late August.

To compare how well the test vaccine works, researchers conduct what is known as a randomized double-blind placebo control study.

In this case, half of the volunteers receive the test vaccine, and the other half receive a placebo or inactive vaccine.

Researchers then follow both groups as they go about their lives, to see if they are infected with the novel coronavirus out in the community.

Neither the trial participants nor the vaccine researchers know which participants receive the test vaccine and which get the placebo until the research is completed and the "blind" is lifted.

All of the participants are carefully followed for adverse side effects.

"We don't know if the participant who had the serious issue is in the vaccine or is in the placebo arm," Dr. del Rio says.  "And, the reality is, you have to do the un-blinding, to do what is needed, and then you decide what to do after that."

In earlier Oxford University COVID-19 vaccine research, over half the study volunteers reported mild to moderate side effects, including fever, headache, soreness at the injection site and muscle pain.

The halting of the Oxford University vaccine trial came on the same day the CEO's of 9 major drug manufacturers and biotech companies, include the heads of AstraZeneca, Pfizer and Moderna, signed a pledge not to push for early FDA approval of a COVID-19 vaccine without sufficient safety and efficacy data.

Dr. del Rio believes the pause in this trial is a sign the system is working.

"If there is any signal, you stop, you observe and you see what happens," del Rio says.  "So, I'm not concerned.  I simply think this is how research works and what we want research to be doing.

AstraZeneca is bringing in an independent review community to look at the safety data.

The company hopes to expedite the investigation, to try to keep its vaccine study on schedule.

The drugmaker hopes to wrap up its clinical trials by late 2020.

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