Just hours after AstraZeneca released results from its US trials promising high efficacy against Covid-19, the US National Institute of Allergy and Infectious Diseases issued an unusual public statement casting doubts over the recency of the data.

A health worker administers a dose of the AstraZeneca/Oxford vaccine at a coronavirus vaccination centre at the Fazl Mosque in southwest London, UK on March 23, 2021.
A health worker administers a dose of the AstraZeneca/Oxford vaccine at a coronavirus vaccination centre at the Fazl Mosque in southwest London, UK on March 23, 2021. (AFP)

AstraZeneca's release of encouraging data about its coronavirus vaccine from its US trial had raised hopes that the drug company could put a troubled rollout behind it.

But just hours after its announcement, American officials issued an unusual statement on Tuesday expressing concern the company had included “outdated information” from its study and that it may have provided “an incomplete view of the efficacy data”.

Coupled with earlier missteps in reporting data and a recent blood clot scare, experts said the new stumble could cause lasting harm to the shot that is key to global efforts to stop the pandemic and erode vaccine confidence more broadly.

“I doubt it was (US officials') intention to deliberately undermine trust in the AstraZeneca vaccine,” said Dr Paul Hunter, a professor of medicine at the University of East Anglia. 

“But this will likely cause more vaccine hesitancy.”

READ MORE: Vaccine flip flop is symbolic of chaos endemic within the EU

Data back-and-forth 

AstraZeneca said on Tuesday that the results it released a day earlier included information through February 17 but appeared to be consistent with more up-to-date data.

It promised an update within 48 hours. 

Those results showed its shot was about 79 percent effective in stopping symptomatic Covid-19 and that there were no severe illnesses or hospitalisations among vaccinated volunteers, compared with five such cases in participants who received dummy shots.

The back-and-forth over the latest release is not the first time the company has run into problems.

READ MORE: WHO panel gives nod to AstraZeneca vaccine

Public rejection

Partial results from its first major trial, which Britain used to authorise the vaccine, were clouded by a manufacturing mistake that researchers didn't immediately acknowledge.

Insufficient data about how well the vaccine protected older people led some countries to initially restrict its use to younger populations before reversing course. 

And US officials suspended an AstraZeneca study for an unusual six weeks while they sought details about problems reported in Britain before deciding the vaccine wasn't to blame.

Then last week, more than a dozen countries temporarily halted their use of the AstraZeneca shot after reports of rare blood clots in some people who received it. The European Medicines Agency concluded the shot did not increase the overall incidence of clots, but the unwanted attention appears to have left a mark.

In Norway, a top official warned on Monday it might not be able to resume its use of the vaccine because so many people were rejecting it.

“People clearly say that they do not want the AstraZeneca vaccine,” Marte Kvittum Tangen, who heads a Norwegian doctors’ association, told broadcaster NRK.

READ MORE: Denmark, Norway, Iceland halt AstraZeneca jab despite EU safety assurance

Perception over science

Last week in Bucharest, Romania, vaccination coordinator Valeriu Gheorghita said 33,000 AstraZeneca immunisation appointments had been cancelled in 24 hours and that about a third of the 10,000 people scheduled to receive the vaccine did not show up.

In Belgrade, Serbia, a sprawling exhibition centre set up for people to get the AstraZeneca vaccine was mostly deserted on Monday.

“This is unfortunately more about perception than it is the science,” said Dr Bharat Pankhania, an infectious diseases specialist at Britain’s University of Exeter.

“We have now seen, on several parametres, that the AstraZeneca vaccine provides protection and is safe,” he said. “But the narrative for the public has not been as clear.”

READ MORE: AstraZeneca data review finds no increased blood clot risk from vaccine

Changing messages

French President Emmanuel Macron initially suggested the vaccine wasn’t effective for older people, before backtracking.

Still, France only authorised AstraZeneca’s vaccine for use in adults 65 and under, citing a lack of data. Then the government changed its mind, based on new data, and said it’s fine for all adults. 

But when there were reports of rare blood clots in some vaccine recipients, the government suspended use of the shot all together. When France restarted AstraZeneca, it banned the shot for anyone under 55.

The whiplash-inducing messages come at a time when France, like much of continental Europe, is struggling to speed up its vaccination drive while also facing a spike in cases that is close to overwhelming its hospitals and prompting threats of new lockdowns.

Even if the company clears up the latest misunderstanding, it could have a lasting impact.

READ MORE: Thailand clears AstraZeneca as possible clotting side effects divide Europe

Cautionary tale

Julian Tang, a virologist at the University of Leicester, pointed to the decades-old controversy over the measles vaccine as a cautionary tale.

“There was absolutely no evidence to prove the (measles, mumps and rubella) vaccine caused autism,” he said. But despite the retraction of the paper that made that claim, Tang said some people still worry about the vaccine.

READ MORE: EU-UK relations hit new low over "vaccine ban" comments

Spreading skepticism 

The tepid support for the AstraZeneca vaccine in Europe stands in contrast to governments in the developing world that are desperate for supplies. 

Because the shot is cheaper and easier to store than those of many rivals, AstraZeneca’s vaccine is expected to be used widely in the poorer countries.

Dr. Bruce Aylward, a senior adviser at the World Health Organisation, said the UN agency has a long list of countries “very keen” to get the shot as soon as possible. “We simply cannot get enough of it,” he said.

But some experts have worried that the scepticism in Europe could eventually cast a pall over the vaccine worldwide. They suggested one measure that could reassure a jittery public about the shot: a green light from the US Food and Drug Administration.

“If the US regulator looks at this data and authorises AstraZeneca, that will carry a lot of weight,” said Jimmy Whitworth, a professor of international public health at the London School of Hygiene and Tropical Medicine.

READ MORE: South Africa looks to J&J vaccine as AstraZeneca disappoints

Burying doubts

AstraZeneca said it would be submitting its data to the FDA within weeks.

It's still possible the vaccine can bury the doubts. At a vaccination centre in Lisbon, 68-year-old Rui Manuel Martins dismissed the concerns, saying millions had been immunised with very few ill effects.

“There’s always some cases of people rejecting any medications,” he said before receiving his first dose. “It’s better to be vaccinated rather than not.”

READ MORE: AstraZeneca Covid-19 vaccine protective against variant first seen in UK

Source: AP