AstraZeneca’s COVID-19 Vaccine Candidate Exhibits Encouraging Data, Promising Features

AstraZeneca’s COVID-19 Vaccine Candidate Exhibits Encouraging Data, Promising Features
Credit: Paul Biris/Getty Images

A third COVID-19 vaccine, AstraZeneca’s AZD1222, is nearing approval following positive results from an interim analysis. The company described the vaccine as “highly effective” in preventing the disease, according to an AZ release. It showed about 62% efficacy based on one analysis, and 90% based on another, or an average 70% overall.  That average figure is noticeably lower than the 90% to 95% efficacy of its competitors from Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273).

Key advantages of AZD1222 are that it does not require ultra-cold storage and it may be the least expensive of the three lead vaccines in development.

Pascal Soriot, AZ CEO, says, “The vaccine’s simple supply chain and our no-profit pledge and commitment to broad, equitable and timely access means it will be affordable and globally available.”

All three of the leading candidate vaccines are mRNA-based, however AZ’s vaccine uses a viral vector for delivery, it also uses the exact wild-type sequence of the Spike protein that is the target for all the COVID-19 vaccines so far. Whether AZD1222’s biological effects differ, thanks to its novel design, waits to be seen and will be key to determining its potential.  So far, all the leading vaccine candidates have been well tolerated.

The preliminary results on the AstraZeneca vaccine were based on two trials comprising 11,363 participants and showed around 62% effectiveness when two full-dose shots were given a month apart. A second analysis, on a subset of the participants showed 90% effectiveness when administered as a half dose followed by a full dose at least a month later. Anthony Fauci, White House coronavirus advisor, has previously said that the threshold for an acceptable vaccine is as low as 50%, which is comparable to certain available vaccines for other diseases.

More than 1.3 million people have died from COVID-19 worldwide since the pandemic began.  The US has been one of the hardest hit countries, reporting more than 3 million new cases so far this month, which is about a quarter of the number of cases seen since the start of the pandemic.  A global surge in cases began early this fall and has been escalating dramatically.

The race for the first COVID-19 vaccine to market has heated up considerably over the last couple weeks and the lead in this race, Pfizer-BioNTech’s vaccine, could start being administered within a few days after approval. Its FDA review is scheduled for Dec. 10. Moderna is also expected to file for emergency approval for its vaccine before the end of this month, and should see review by Dec. 17. AZ is still well positioned, not just because of the vaccine’s potential advantages, but because the company already has contracts to distribute billions of doses of the vaccine in the U.S., Europe, and India, starting early next year.

The AZ vaccine was developed in collaboration with researchers at the University of Oxford and tested first in the UK and Brazil. AZ has announced it will not profit from sales of the vaccine, which is expected to cost around $3 per dose. The Pfizer-BioNTech and Moderna vaccines are expected to cost four times that, according to a Reuters report.


In other COVID-19 vaccine-related news:

On Saturday, Moncef Slaoui, head of the U.S.’s operation “Warp Speed,” laid out a near-term timeline for COVID-19 vaccine progress on ABC News’ “This Week with George Stephanopoulos.” Pfizer and BioTech N’s candidate is scheduled for FDA review on Dec. 10, and Moderna is expected to have its FDA review before the month is out.  Both companies aim to ship vaccine to distributers within a day after review. Vaccinations could begin within days after that. Slaoui also mentioned the problem of hesitancy around an approved COVID shot, not just from the public, but among healthcare workers, doctors and nurses, which he said was “unfortunate.”

A report from the Trump administration last week said there was “tremendous uptake” of its program to allow CVS Heath and Walgreens to administer COVID-19 vaccines to seniors in long-term care facilities. Health and Human Services Secretary Alex Azar reported that 99% of skilled nursing facilities in the US have signed up for the program.

A Reuters report says the organization Medecins Sans Frontieres (MSF) is calling for AZ to make its supply contracts public to prove its claims that its COVID-19 vaccine will be the most affordable of the three candidates heading to market. AZ has announced it will not profit from sales of its vaccine.

A report from CNBC warns that the CDC must be transparent about side effects or there could be backlash against the vaccines. The report quotes Sandra Fryhofer of the American Medical Association, who points out that both Pfizer and Moderna’s vaccines are administered as two separate shots and can induce side effects including muscle pain, chills and headache, which are similar to mild COVID-19 symptoms. Fryhofer worries that patients may skip the second shot if they experience unpleasant side effects after the first.

Analysts who appeared on CNBC yesterday said it was “challenging” to compare the efficacy of the three vaccines currently in the lead for approval, because of difference in how the trials were conducted.  The AZ trials included weekly testing with swabbing to detect the virus among participants, the company also used a meningococcal vaccine for comparison instead of a true placebo, with no activity at all.