3 promising preliminary details from the Oxford-AstraZeneca vaccine trial

24 Nov 2020

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University of Southampton’s Dr Michael Head explains why he believes the Oxford-AstraZeneca vaccine could be a global game changer.

Read about the Covid-19 vaccine on The Conversation

A version of this article was originally published by The Conversation (CC BY-ND 4.0)

In the long dark tunnel that has been 2020, November stands out as the month that light appeared. Some might see it as a bright light, others as a faint light – but it is unmistakably a light.

On 9 November, Pfizer announced the interim results of its candidate vaccine, showing it to be “more than 90pc effective” in preventing symptomatic Covid-19 in late-stage human trials. The news was greeted with joy.

A couple of days later, the Russian Direct Investment Fund announced that the candidate vaccine it is funding – dubbed Sputnik V – showed 92pc efficacy in late-stage trials. Not to be outdone, Moderna then announced that its candidate vaccine showed 94.5pc efficacy.

‘With promises for equitable vaccine distribution, there is hope that the poorer populations around the world will not be forgotten’

The latest Covid-19 vaccine announcement comes from Oxford University. And, as with all of the above announcements, it came via press release. Its vaccine candidate, developed in partnership with AstraZeneca, showed an overall effectiveness of 70.4pc.

There were no cases of severe Covid-19 in those who received the Oxford-AstraZeneca vaccine, and it seems to generate a protective immune response in older people. However, we’ll have to wait for the final breakdown of results to get clarification on that.

And while the Oxford vaccine reports lower overall effectiveness than the Pfizer or Moderna vaccines – at least at this interim stage – there are other success factors to consider.

1. Lower doses would mean more vaccine to go around

In case that Oxford result sounds disappointing, bear in mind that these are interim results and the figures might change. Also, the Oxford vaccine was given to one group of volunteers as two standard doses, which showed 62pc effectiveness. Another group of volunteers received a smaller dose followed by a standard second dose, which raised effectiveness to 90pc.

It’s not immediately clear why this is the case. Prof Andrew Pollard, one of the lead researchers on the project, described the results as “intriguing”. He also highlighted that the use of lower doses means that there would be more vaccine doses available.

Safety is another factor to consider, and the Oxford vaccine is so far reported to have a good safety record with no serious side-effects.

2. Easier to store

Another crucial factor is storage. The Oxford vaccine can be stored in a domestic fridge at 2 to 8 degrees Celsius and distributed using existing logistics.

The need for sustained freezing across the whole vaccine journey from factory to clinic at ultra-low temperatures – as seen with the Pfizer vaccine – may be a problem for many countries, but especially poorer countries.

3. Equitable distribution

The Oxford vaccine, based on a viral vector, is cheaper at $3 to $5 a dose compared to Pfizer and Moderna’s mRNA vaccines, priced at $19.50 and up to $37 per dose, respectively.

Equitable distribution of new vaccines is vital, especially for low and middle-income countries that don’t have the profile or purchasing power of wealthier countries. GAVI – a global health partnership that aims to increase access to immunisation in poor countries – has worked for years to address this very point. It set up the Covax initiative in 2020, which has access to 700m doses of Covid vaccine if clinical trials are successful.

According to the BBC, AstraZeneca has made a “no-profit pledge” on its vaccine and, along with Oxford University, has committed to provide a billion doses of their vaccine for low and middle-income countries, starting with 400m doses before the end of 2020. Certainly, AstraZeneca has committed to provide more doses to countries outside of Europe and the US than any of its nearest competitors.

An excellent start, but challenges ahead

These commitments will clearly not be enough for immediate global coverage, but it is an excellent start. The World Bank estimates that the world’s population living in extreme poverty will rise above 9pc this year, and the health systems around these people are fragile. With promises for equitable vaccine distribution, there is hope that the poorer populations around the world will not be forgotten. The global health community must keep its focus on this area.

What does this announcement mean for the world? Potentially a huge amount. But remember that the trials are not yet complete and, at the time of writing, the regulators have yet to approve any of the new vaccine candidates.

Even when those hurdles are cleared, we still need to vaccinate the world, which requires successfully navigating the complex obstacles of distance, terrain, politics, cold-chain logistics and human behaviour.

The global pandemic is not over and won’t be for a long time yet – but the light is getting brighter.

The Conversation

By Dr Michael Head

Dr Michael Head is a senior research fellow in global health at the University of Southampton. He has a background in public health research and infectious disease epidemiology, with research links in Ghana, Togo, Ethiopia and Brazil.