Skip to main content
The Globe and Mail
Support Quality Journalism.
The Globe and Mail
First Access to Latest
Investment News
Collection of curated
e-books and guides
Inform your decisions via
Globe Investor Tools
Just$1.99
per week
for first 24 weeks

Enjoy unlimited digital access
Enjoy Unlimited Digital Access
Get full access to globeandmail.com
Just $1.99 per week for the first 24 weeks
Just $1.99 per week for the first 24 weeks
var select={root:".js-sub-pencil",control:".js-sub-pencil-control",open:"o-sub-pencil--open",closed:"o-sub-pencil--closed"},dom={},allowExpand=!0;function pencilInit(o){var e=arguments.length>1&&void 0!==arguments[1]&&arguments[1];select.root=o,dom.root=document.querySelector(select.root),dom.root&&(dom.control=document.querySelector(select.control),dom.control.addEventListener("click",onToggleClicked),setPanelState(e),window.addEventListener("scroll",onWindowScroll),dom.root.removeAttribute("hidden"))}function isPanelOpen(){return dom.root.classList.contains(select.open)}function setPanelState(o){dom.root.classList[o?"add":"remove"](select.open),dom.root.classList[o?"remove":"add"](select.closed),dom.control.setAttribute("aria-expanded",o)}function onToggleClicked(){var l=!isPanelOpen();setPanelState(l)}function onWindowScroll(){window.requestAnimationFrame(function() {var l=isPanelOpen(),n=0===(document.body.scrollTop||document.documentElement.scrollTop);n||l||!allowExpand?n&&l&&(allowExpand=!0,setPanelState(!1)):(allowExpand=!1,setPanelState(!0))});}pencilInit(".js-sub-pencil",!1); // via darwin-bg var slideIndex = 0; carousel(); function carousel() { var i; var x = document.getElementsByClassName("subs_valueprop"); for (i = 0; i < x.length; i++) { x[i].style.display = "none"; } slideIndex++; if (slideIndex> x.length) { slideIndex = 1; } x[slideIndex - 1].style.display = "block"; setTimeout(carousel, 2500); } //

A researcher works on the coronavirus vaccine developed by AstraZeneca and Oxford University in a laboratory at the Jenner Institute in Oxford.

John Cairns/The Associated Press

AstraZeneca is likely to run an additional global trial to assess the efficacy of its COVID-19 vaccine using a lower dosage, its chief executive was quoted as saying on Thursday amid questions over the results from its late-stage study.

Instead of adding the trial to an ongoing U.S. process, AstraZeneca might launch a fresh study to evaluate a lower dosage of its vaccine that performed better than a full dosage, Pascal Soriot was quoted as saying in a Bloomberg News report.

“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” he said.

Story continues below advertisement

Soriot said it would probably be another “international study, but this one could be faster because we know the efficacy is high so we need a smaller number of patients.”

The news comes as AstraZeneca faces questions about its success rate that some experts say could hinder its chances of getting speedy U.S. and EU regulatory approval.

Several scientists have raised doubts about the robustness of results released on Monday showing the experimental vaccine was 90% effective in a subgroup of trial participants who, by error initially, received a half dose followed by a full dose.

Soriot said he did not expect the additional trial to delay U.K. and European regulatory approvals.

COVID-19 news: Updates and essential resources about the pandemic

Is my city going back into lockdown? A guide to COVID-19 restrictions across Canada

How many coronavirus cases are there in Canada, by province, and worldwide? The latest maps and charts

Asked about the Bloomberg report, an AstraZeneca spokesman said there was “strong merit in continuing to further investigate the half-dose/ full dose regimen.”

“We are further evaluating the data and will work with regulators on the best approach for further evaluation,” he said.

“This would add to data from existing trials which are currently being prepared for regulatory submission.”

Story continues below advertisement

AstraZeneca told Reuters earlier on Thursday that administering of the half dose had been reviewed and approved by independent data safety monitors and the U.K. regulator, adding that the regulator publicly confirmed there was “no concern”.

Clearance from the U.S. Food and Drug Administration (FDA) may take longer though because the agency is unlikely to approve the vaccine based on studies carried out elsewhere, especially given the questions over the results, Soriot said.

Authorization in some countries is still expected before the end of the year, he added.

AstraZeneca research chief Mene Pangalos told Reuters on Monday that researchers had stumbled upon the half-dose regime by accident, saying a subgroup of the trial was given a smaller initial dose by mistake.

Earlier he had said that the firm would start discussions with the FDA to change the design of its experimental COVID-19 vaccine trial to add the more-effective dosage regime.

Running an additional trial might not be too much of a complication for the British drugmaker in the race to develop a successful vaccine to help tame the pandemic, which has killed more than a million people and roiled the global economy.

Story continues below advertisement

Helen Fletcher, professor of immunology at the London School of Hygiene & Tropical Medicine, said that another trial would not necessarily delay getting a green light as efficacy in the higher dose regime still met the World Health Organization’s target, and it was not unusual to run new studies on approved vaccines.

“It’s entirely possible AZ and Oxford could license the high dose and then quickly seek an amendment to use the low dose when they have sufficient data,” she said.

The vaccine is one of three that could get approved before the end the year. Earlier this month, Pfizer and Moderna reported that their vaccines were about 95% effective in preventing illness, setting the bar sky-high.

Even so, the AstraZeneca shot developed with Oxford University is cheaper to make, easier to distribute and faster to scale up than its rivals.

A peer-reviewed analysis of the trial data will be published in a medical journal in the coming weeks.

The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) is continuing its rolling review of the vaccine, the regulator’s Chief Executive June Raine said in an e-mail on Thursday.

Story continues below advertisement

“Any vaccine must undergo robust clinical trials in line with international standards, with oversight provided by the Medicines and Healthcare products Regulatory Agency (MHRA), and no vaccine would be authorized for supply in the U.K. unless the expected standards of safety, quality and efficacy are met,” she said.

The European Medicines Agency did not immediately respond to requests for comment on the potential for another study.

Countries around the world are working on a coronavirus vaccine, including right here in Canada. Globe and Mail science reporter Ivan Semeniuk discussed the timeline and challenges in developing COVID-19 vaccines during a Facebook live. The Globe and Mail

Our Morning Update and Evening Update newsletters are written by Globe editors, giving you a concise summary of the day’s most important headlines. Sign up today.

Your Globe

Build your personal news feed

  1. Follow topics and authors relevant to your reading interests.
  2. Check your Following feed daily, and never miss an article. Access your Following feed from your account menu at the top right corner of every page.

Follow topics related to this article:

View more suggestions in Following Read more about following topics and authors
Coronavirus information
Coronavirus information
The Zero Canada Project provides resources to help you manage your health, your finances and your family life as Canada reopens.
Visit the hub
Report an error
Due to technical reasons, we have temporarily removed commenting from our articles. We hope to have this fixed soon. Thank you for your patience. If you are looking to give feedback on our new site, please send it along to feedback@globeandmail.com. If you want to write a letter to the editor, please forward to letters@globeandmail.com.

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff.

We aim to create a safe and valuable space for discussion and debate. That means:

  • Treat others as you wish to be treated
  • Criticize ideas, not people
  • Stay on topic
  • Avoid the use of toxic and offensive language
  • Flag bad behaviour

If you do not see your comment posted immediately, it is being reviewed by the moderation team and may appear shortly, generally within an hour.

We aim to have all comments reviewed in a timely manner.

Comments that violate our community guidelines will not be posted.

Read our community guidelines here

Discussion loading ...

To view this site properly, enable cookies in your browser. Read our privacy policy to learn more.
How to enable cookies