AstraZeneca halting COVID-19 vaccine trial is "one of the safety valves," Dr. Fauci says

Dr. Fauci on the race for a COVID-19 vaccine
Dr. Fauci on the race for a COVID-19 vaccine 05:32

The halting of AstraZeneca's coronavirus vaccine trial is "not uncommon," Dr. Anthony Fauci, the nation's top infectious disease expert, said Wednesday. Being alert for potential adverse reactions is part of the process, he explained. 

"It's really one of the safety valves that you have on clinical trials such as this," he said on "CBS This Morning." "So it's unfortunate that it happened. Hopefully they'll work it out and be able to proceed along with the remainder of the trial."

AstraZeneca paused its Phase 3 trial on Tuesday after one participant became ill. It was not clear what symptoms the participant had. AstraZeneca is one of three companies currently in the final phase of vaccine trials. 

"This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials," AstraZeneca said in a statement.

Fauci said "generally," the adverse event is related to something else, not the vaccine, but those running the trial can't presume that. 

"You always make the presumption that it's due directly to the actual vaccine or therapeutic or whatever it is that's in the clinical trial," he said. "That's the reason why when we say we do careful safety types of studies, this is an example of the kind of thing that you do to make sure we're dealing with a product that's safe."

Fauci, who is on the White House Coronavirus Task Force, also stuck by his earlier projection that the safety and effectiveness of a vaccine will be known by the end of the year.

"Likely November, December. Is it possible? Is it conceivable that we could find out earlier, let's say October? Certainly that's possible. I think it's unlikely, but you can't rule it out," he said. "I think the more likely scenario is that we will know by the end of this calendar year and hopefully we'll be able to start vaccinations in earnest as we begin 2021."

President Donald Trump has expressed optimism that a vaccine would be ready ahead of the 2020 presidential election on November 3, despite health experts saying that is unlikely. 

Asked about the politicization of the race for a vaccine, Fauci said he hopes and believes the authorization will not be politicized. 

"When the decision is made whether or not you're going to give an EUA, which is an emergency use authorization, or even approve the vaccine, there are also advisory boards that you run this by," he said. "There's really a lot of transparency in that, so I do hope and I believe there won't be a politicization of this. It may be a political atmosphere, but I don't think we're going to have a politicization of the actual decisions regarding a vaccine."

Fauci also said there are other "safety valves" throughout the trial process, including "independent data and safety monitoring boards that look at the data intermittently on a regular basis to determine just what the status of the trial is."