FILE - In this Aug. 14, 2020, file photo, laboratory technicians work at the mAbxience biopharmaceutical company on an experimental coronavirus vaccine developed by Oxford University and the laboratory AstraZeneca in Garin, Argentina. AstraZeneca announced Monday, Aug. 31, its vaccine candidate has entered the final testing stage in the U.S. (AP Photo/Natacha Pisarenko, File)

FILE - In this Aug. 14, 2020, file photo, laboratory technicians work at the mAbxience biopharmaceutical company on an experimental coronavirus vaccine developed by Oxford University and the laboratory AstraZeneca in Garin, Argentina. AstraZeneca announced Monday, Aug. 31, its vaccine candidate has entered the final testing stage in the U.S. (AP Photo/Natacha Pisarenko, File)

AstraZeneca COVID-19 vaccine study paused after one illness

An AstraZeneca spokesperson confirmed the pause in vaccinations covers studies in the U.S. and other countries

Late-stage studies of AstraZeneca’s COVID-19 vaccine candidate are on temporary hold while the company investigates whether a recipient’s “potentially unexplained” illness is a side effect of the shot.

In a statement issued Tuesday evening, the company said its “standard review process triggered a pause to vaccination to allow review of safety data.”

AstraZeneca didn’t reveal any information about the possible side effect except to call it “a potentially unexplained illness.” The health news site STAT first reported the pause in testing, saying the possible side effect occurred in the United Kingdom.

An AstraZeneca spokesperson confirmed the pause in vaccinations covers studies in the U.S. and other countries. Late last month, AstraZeneca began recruiting 30,000 people in the U.S. for its largest study of the vaccine. It also is testing the vaccine, developed by Oxford University, in thousands of people in Britain, and in smaller studies in Brazil and South Africa.

Two other vaccines are in huge, final-stage tests in the United States, one made by Moderna Inc. and the other by Pfizer and Germany’s BioNTech. Those two vaccines work differently than AstraZeneca’s, and the studies already have recruited about two-thirds of the needed volunteers.

Temporary holds of large medical studies aren’t unusual, and investigating any serious or unexpected reaction is a mandatory part of safety testing. AstraZeneca pointed out that it’s possible the problem could be a coincidence; illnesses of all sorts could arise in studies of thousands of people.

“We are working to expedite the review of the single event to minimize any potential impact on the trial timeline,” the company statement said.

It’s likely the unexplained illness was serious enough to require hospitalization and not a mild side effect such as fever or muscle pain, said Deborah Fuller, a University of Washington researcher who is working on a different COVID-19 vaccine that has not yet started human testing.

“This is not something to be alarmed about,” Fuller said. Instead, it’s reassuring that the company is pausing the study to figure out what’s happening and carefully monitoring the health of study participants.

Dr. Ashish Jha of Brown University said via Twitter that the significance of the interruption was unclear but that he was “still optimistic” that an effective vaccine will be found in the coming months.

“But optimism isn’t evidence,” he wrote. “Let’s let science drive this process.”

Angela Rasmussen, a virologist at Columbia University in New York, tweeted that the illness may be unrelated to the vaccine, “but the important part is that this is why we do trials before rolling out a vaccine to the general public.”

During the third and final stage of testing, researchers look for any signs of possible side effects that may have gone undetected in earlier patient research. Because of their large size, the studies are considered the most important study phase for picking up less common side effects and establishing safety.

The trials also assess effectiveness by tracking who gets sick and who doesn’t between patients getting the vaccine and those receiving a dummy shot.

The development came the same day that AstraZeneca and eight other drugmakers issued an unusual pledge, vowing to uphold the highest ethical and scientific standards in developing their vaccines.

The announcement follows worries that President Donald Trump will pressure the U.S. Food and Drug Administration to approve a vaccine before it’s proven to be safe and effective.

The U.S. has invested billions of dollars in efforts to quickly develop multiple vaccines against COVID-19. But public fears that a vaccine is unsafe or ineffective could be disastrous, derailing the effort to vaccinate millions of Americans.

Representatives for the FDA did not immediately respond to requests for comment Tuesday evening.

AstraZeneca’s U.S.-traded shares fell more than 6% in after-hours trading following reports of the trial being paused.

___

Associated Press writers Matthew Perrone and Carla K. Johnson contributed to this report.

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

Lauran Neergaard, The Associated Press

Coronavirusvaccines

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

(Photo from Highway 11 Functional Planning Study)
Public input wanted for Highway 11 improvement plan

Round 2 of public online engagement continues until March 10

File photo
Gov’t of Alberta identifies estimated 300 new COVID-19 cases Sunday

Online COVID-19 dashboard unavailable as upgrades being completed

COVID
Red Deer down to 313 active cases of COVID-19

Alberta reports an additional 411 COVID-19 cases

Seniors in the 65-unit Piper Creek Lodge are among those waiting for COVID-19 vaccinations. (File photo by Advocate staff)
Central Alberta senior lodges anxiously waiting for COVID-19 vaccinations

“Should be at the front of the line, not the back of the line”

Elvira D’Angelo, 92, waits to receive her COVID-19 vaccination shot at a clinic in Montreal, Sunday, March 7, 2021, as the COVID-19 pandemic continues in Canada and around the world. THE CANADIAN PRESS/Graham Hughes
‘It’s been a good week’: Tam hopeful on vaccines as pandemic anniversary nears

Tam says the addition of two new vaccines will help Canadians get immunized faster

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. THE CANADIAN PRESS/Nathan Denette
Vaccine hesitancy decreases in B.C. as mass immunizations set to begin: poll

Two-thirds of British Columbians, and Canadians, would get the vaccine as soon as possible

A woman walks through Toronto’s financial district on Monday, July 30, 2018. A new poll suggests most Canadians believe there’s still a long way to go to achieve gender equality in this country. THE CANADIAN PRESS/Graeme Roy
Canadians, especially women, say gender equality not achieved in Canada: Poll

Poll results themselves underscore the challenge, with more men believing equality had been achieved

This image provided by Harpo Productions shows Meghan, The Duchess of Sussex, left, in conversation with Oprah Winfrey. (Joe Pugliese/Harpo Productions via AP)
Race, title and anguish: Meghan and Harry explain royal rift

Meghan said she struggled with concerns within the royal family about her son’s skin colour

Kiara Robillard is seen in an undated handout photo. When the pandemic began, Robillard had to rush back home to Alberta from California, where she had been living for five years, after she was struck by a truck that broke her spine in two places. THE CANADIAN PRESS/HO-Kiara Robillard, *MANDATORY CREDIT*
‘It kind of clicks:’ Text4Hope program helps with depression, anxiety during pandemic

Participants receive one text message every morning for three months

(The Canadian Press)
‘Worse than Sept. 11, SARS and financial crisis combined’: Tourism industry in crisis

Travel services saw the biggest drop in active businesses with 31 per cent fewer firms operating

Hockey hall-of-fame legend Wayne Gretzky, right, watches the casket of his father, Walter Gretzky, as it is carried from the church during a funeral service in Brantford, Ont., Saturday, March 6, 2021. HE CANADIAN PRESS/Nathan Denette
Walter Gretzky remembered as a man with a ‘heart of gold’ at funeral

The famous hockey father died Thursday at age 82 after battling Parkinson’s disease

Supporters rally outside court as Pastor James Coates of GraceLife Church is in court to appeal bail conditions, after he was arrested for holding day services in violation of COVID-19 rules, in Edmonton, Alta., on Thursday March 4, 2021. THE CANADIAN PRESS/Jason Franson
‘Law remains valid:’ Pastor accused of violating health orders to remain in jail

The Justice Centre for Constitutional Freedoms is representing the pastor

A decommissioned pumpjack is shown at a well head on an oil and gas installation near Cremona, Alta., Saturday, Oct. 29, 2016. The Alberta Energy Regulator says it is suspending all of the licences held by an oil and gas producer with more than 2,200 wells and 2,100 pipelines after it failed to bring its operations into compliance. THE CANADIAN PRESS/Jeff McIntosh
Alberta Energy Regulator suspends licences of oil and gas producer that owes $67M

The company is being asked to comply with past orders to clean up historic spills and contamination

Most Read