Oxford-AstraZeneca vaccine shows 70% overall efficacy, more work needed: study

Click to play video: 'Canada could get first COVID-19 vaccines next week' Canada could get first COVID-19 vaccines next week
WATCH ABOVE: Canada could get first COVID-19 vaccines next week – Dec 7, 2020

AstraZeneca and Oxford University have more work to do to confirm whether their COVID-19 vaccine can be 90 per cent effective, peer-reviewed data published in The Lancet showed on Tuesday, potentially slowing its eventual rollout in the fight against the pandemic.

Once seen as the frontrunner in the development of a vaccine against the coronavirus crisis, the British team were overtaken by U.S. drugmaker Pfizer, whose shots – with a success rate of around 95 per cent – were administered to UK pensioners on Tuesday in a world-first hailed as V-Day.

Read more: AstraZeneca releases coronavirus vaccine data. Here’s what Canadians should know

Detailed results from the AstraZeneca/Oxford trials have been eagerly awaited after some scientists criticized a lack of information in their initial announcement last month.

Story continues below advertisement

However, the Lancet study gave few extra clues about why efficacy was 62 per cent for trial participants given two full doses, but 90 per cent for a smaller sub-group given a half, then a full dose.

“(This) will require further research as more data becomes available from the trial,” the study said.

Less than 6 per cent of UK trial participants were given the lower dose regimen and none of them was aged over 55, meaning more research will be needed to investigate the vaccine’s efficacy in older people who are particularly susceptible to COVID-19.

Click to play video: 'AstraZeneca-Oxford COVID-19 vaccine looks promising, 70% effective on average' AstraZeneca-Oxford COVID-19 vaccine looks promising, 70% effective on average
AstraZeneca-Oxford COVID-19 vaccine looks promising, 70% effective on average – Nov 23, 2020

Pooling the results, overall efficacy was 70.4%, the data on Tuesday showed. That is above the 50 per cent minimum set by the U.S. Food and Drug Administration.

[ Sign up for our Health IQ newsletter for the latest coronavirus updates ]

COVID-19 vaccines from Pfizer/BioNTech and Moderna have reported efficacy levels of more than 90 per cent in late stage trials.

Story continues below advertisement

But the AstraZeneca/Oxford vaccine is seen as particularly important to tackling the pandemic in the developing world, as it would be cheaper and easier to distribute.

“The basic message that the overall efficacy across the trials that are reported here is about 70 per cent but with a clear description of its uncertainty,” said Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine.

“The statistical uncertainty is that the efficacy could be as low as 55% or as high as 80%. The Pfizer/BioNTech and Moderna vaccines both have efficacies above 90% and are clearly more efficacious under trial conditions.”

Read more: ‘Unpredictable pathogen’: New coronavirus study highlights severity of illness

Asked whether the half, then full dose regimen had been a mistake, Andrew Pollard, director of the Oxford Vaccine Group and chief investigator into the trials, told a news conference it had been “unplanned.”

Head of AstraZeneca’s non-oncology research and development, Mene Pangalos, said he hoped requests for approval from regulators around the globe could still be submitted this year.

“We hope that once the regulatory authorities review the data, we can get approval any time from the completion of the submission, which could be any time from the end of this year to early next year,” he said.

Story continues below advertisement
Click to play video: 'Mass COVID-19 vaccination rollout begins in the U.K.' Mass COVID-19 vaccination rollout begins in the U.K.
Mass COVID-19 vaccination rollout begins in the U.K – Dec 8, 2020

However, Pollard conceded the different results from the two dosage regimens complicated matters.

“The regulators will decide exactly what their label should say,” he said, when asked whether regulators might approve the two full shots regiment first, and then potentially the half, then full, shot regiment when more data is in.

Pangalos also said he assumed U.S. regulators would want to see results from an ongoing trial in the United States before giving their approval.

The Oxford researchers said the vaccine was found to be safe, with three out of the roughly 23,700 participants experiencing serious conditions that were possibly related to either the COVID-19 vaccine or a standard meningitis vaccine given to a control group.

A case of a serious neurological illness, transverse myelitis, was reported 14 days after a COVID-19 vaccine booster shot, which was “possibly related to vaccination,” they said.

Story continues below advertisement

This case had led to a seven-week trial suspension in the United States and to brief halts in trials in other countries.

A case of fever above 40°C occurred in South Africa, but it was not disclosed whether this participant received the vaccine because the person recovered quickly and is continuing the trial without knowledge of the shot received, as is the norm.

— With reporting by Ludwig Burger, Reuters

Sponsored content