AstraZeneca Will Do More Testing of COVID Vaccine, CEO Says

Ralph Ellis

November 30, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Pharmaceutical company AstraZeneca will conduct more clinical trials to clear up questions about the effectiveness of its coronavirus vaccine, the company CEO told Bloomberg News.

"Now that we've found what looks like a better efficacy, we have to validate this, so we need to do an additional study," CEO Pascal Soriot said.

He said the company probably would do another "international study, but this one could be faster because we know the efficacy is high, so we need a smaller number of patients."

AstraZeneca announced November 23 that its two-shot coronavirus vaccine is on average 70% effective in preventing COVID-19 — a figure reached from two different dosing plans.

One group of participants unintentionally received half a dose followed by a full dose for 90% effectiveness. The second group got two full doses for 62% effectiveness.

Bloomberg said AstraZeneca and its partner, Oxford University, didn't initially reveal the differences in dosing, raising questions about transparency in the clinical trials.

More clinical trials should be done, a Johns Hopkins University professor said.

"At the end of the day it's  probably going to mean they need to restart a good bit of their phase three clinical trial to make sure they get the right data for that highly effective dosing schedule they found by chance," Andrew Pekosz, a virologist and Johns Hopkins Bloomberg School of Public Health Professor, told Bloomberg News in an interview aired Saturday.

Because COVID vaccines are under great scrutiny by scientists and the public, AstraZeneca must address the question of how the dosing difference occurred -- even if it's just a communications problem.

"Every small mistake that's being made is amplified," he said. "A lack of communication about what's going on just doesn't serve the public interest because it fosters some doubts about a vaccine that may in fact be quite good."

Soriot said he did not think extra testing would delay regulatory approvals in the United Kingdom and the European Union. The UK government has been hoping to make the AstraZeneca vaccine publicly available before the end of the year.

UK officials have voiced support for the vaccine this week.

"The headline result is the vaccine works and that's very exciting," Patrick Vallance, the United Kingdom's top scientific advisor, said during a news conference on Thursday, according to CNBC.

"The key thing from our point of view is to leave this in the hands of the regulator," the government's chief medical advisor, Chris Whitty, said at the news conference. "They will make an assessment with lots of data that is not currently in the public domain on efficacy and on safety."

Much of the criticism of AstraZeneca is coming from the United States, and it's unclear what effect the testing glitch will have on the company's efforts to have the vaccine distributed in the United States.

Moncef Slaoui, the leader of Operation Warp Speed, the US government's program to rapidly develop a vaccine, said he was concerned because the 90% effectiveness only came for a small number of participants in the lowest risk group, people below age 55, CNBC said.

Two other vaccine makers, Pfizer and Moderna, said earlier this month their vaccines were about 95% effective. Both companies hope to receive US government approval in December.


Bloomberg News. "Astra Eyes Extra Global Vaccine Trial as Questions Mount"

WebMD. "AstraZeneca Says COVID-19 Vaccine 70% Effective"

Bloomberg News. "AstraZeneca Vaccine Trial Likely Needs a Restart: Johns Hopkins"

CNBC. "Britain tries to cool AstraZeneca concerns as its CEO touts a new vaccine trial"