Why Oxford-AstraZeneca COVID Vaccine Could Be More Important Than Pfizer and Moderna's in Ending Pandemic

The COVID-19 vaccine being developed by British-Swedish pharmaceutical giant AstraZeneca with the University of Oxford could be key to curbing the pandemic in many low- and middle-income countries, despite its seemingly lower effectiveness compared to the other leading candidates, experts have said.

On Monday, AstraZeneca and Oxford announced interim data from its large Phase III trial indicated that its vaccine candidate is "effective at preventing COVID-19 and offers a high level of protection."

How effective is each vaccine?

The news follows announcements over the past month from U.S. companies Pfizer and Moderna, and the Russian Gamaleya Research Institute that their vaccine candidates have an efficacy of 95 percent, 95 percent and 92 percent respectively.

AstraZeneca and Oxford tested two different dose regimens in their study: one group were given a half dose followed by a full dose, while another were given two full doses.

In the latter group, the vaccine was found to have an efficacy of 62 percent, while in the former efficacy rose to around 90 percent.

When combining data from the two dosing regimens, Oxford and AstraZeneca said the vaccine is 70.4 percent effective—although we still have to wait for the conclusion of the study and publication of the results in a peer-reviewed scientific journal before the effectiveness of the jab can be fully assessed.

The graphic below, provided by Statista, shows the effectiveness of the top COVID-19 vaccine candidates.

covid, vaccine, candidates
How effective are the COVID-19 vaccine candidates? Statista

Despite the seemingly lower efficacy compared to the other leading candidates, the scientific community has welcomed the AstraZeneca-Oxford announcement given that the candidate appears to comfortably surpass the minimum threshold of 50 percent efficacy that is usually required by regulators.

In addition, the AstraZeneca-Oxford candidate appears to have some key advantages over its peers: it is much cheaper and easier to distribute.

What are AstraZeneca's advantages?

According to the developers, the vaccine also reduces virus transmission as well as illness—although this has yet to be confirmed. Most experts think that if a vaccine prevents illness it will also prevent transmission to a greater or lesser extent.

Scientists think that having several safe and effective vaccines is key to bringing the pandemic to an end, but the advantages of the AstraZeneca-Oxford vaccine could mean it has a wider reach, even if it turns out to have slightly less efficacy.

"It's a really exciting day," chief investigator for the vaccine, Professor Andrew Pollard from Oxford, said at a press conference. "We have a vaccine for the world... It's effective, prevents hospitalization. It can be stored at fridge temperature and distributed through the normal system."

COVID-19 vaccine, AstraZeneca, oxford
An illustration picture shows vials with COVID-19 Vaccine stickers attached and syringes with the logo of British pharmaceutical company AstraZeneca on November 17, 2020. JUSTIN TALLIS/AFP via Getty Images

Dr. Colin Butter, from the University of Lincoln, in the U.K., said the vaccine offers a "clear pathway out of the present pandemic" and "advantages" over the Pfizer and Moderna candidates.

"Firstly, it requires only a conventional cold chain, used for many products by every surgery and pharmacy in the county," Butter said in a statement.

"Secondly, although the manufacturers have not reported the number of doses presently available ... a reduced priming dose further reduces the actual requirement. Lastly, the trial provides evidence that the vaccine reduces not only clinical disease but also onwards transmission, giving the possibility of achieving head immunity."

Professor Stephen Evans from the London School of Hygiene & Tropical Medicine said the fact that the vaccine can be stored in ordinary refrigerators is helpful in high-income countries, but is of "enormous importance for low-income countries," enabling more equitable access.

Which countries will get vaccines first?

AstraZeneca have said it will provide the vaccine to all nations on a not-for-profit basis for as long as the COVID outbreak is designated a pandemic. For developing nations, this deal will last indefinitely.

The pharmaceutical firm has said its jab will cost between $3 and $4 for a single dose under this approach, which is significantly less than what Pfizer and Moderna are currently charging for their candidates which are based on mRNA technology.

"It is unquestionably more good news for the COVID pandemic, and given its much lower price, this could be the vaccine that reaches more parts of the global community than the mRNA vaccines," Dr. Gillies O'Bryan-Tear from the Faculty of Pharmaceutical Medicine, also in the U.K., said in a statement.

In fact, the AstraZeneca-Oxford accounts for more than 40 percent of the doses going to lower- and middle-income nations, according to deals tracked by London-based research firm Airfinity, Bloomberg reported.

Meanwhile, wealthier nations have already snapped up most of the initial supplies of the Pfizer and Moderna shots. The U.S. for example has ordered 100 million doses of the Pfizer vaccine contender, while Moderna has also committed to supply the country with another 100 million doses.

Lower- and middle-income nations—where most of the global population live—are also reliant on other vaccine candidates from the likes of Novavax Inc. and Johnson & Johnson. But AstraZeneca has said it has the capacity to manufacture around three billion doses in 2021—roughly a third of all the doses that have been committed by various developers.

"There's a lot riding on the Astra vaccine," Suerie Moon, co-director of the Global Health Centre at the Graduate Institute of International and Development Studies in Geneva, told Bloomberg. For lower-income countries, "it's huge."

The vaccine will also be produced in several countries around the world, including India and Brazil, which will help to fast-track its roll-out.

"This is a watershed moment for the world. To have an economically viable vaccine that is up to 90 percent effective, that can be stored at fridge temperature and distributed across the whole planet, gives us real hope of ending this terrible pandemic," Denis Mizne, CEO of the non-profit Lemann Foundation—which established the very first trial of the Oxford-AstraZeneca vaccine in São Paulo, Brazil—said in a statement.