Whereas Pfizer’s jab makes uses of cutting-edge RNA technology to provoke an immune response in humans, the Oxford vaccine utilises an engineered viral vector to train the body in neutralising any future infection from Sars-CoV-2 – the virus that causes Covid-19.
The Oxford vaccine is expected to be easier to store and distribute throughout the UK than the Pfizer jab – if and when it is proved to be safe and effective.
No 10 has ordered millions of doses from the two leading candidates, with experts saying that the government will need a “toolbox” of vaccines to bring the pandemic under control, though concern has been raised over the logistical challenges of storing and transporting the Pfizer jab.
The vaccine needs to be kept at -70C up until the day it is used to maintain the integrity of the doses’ genetic material.
This is expected to complicate the rollout of doses to GP clinics and care homes, which do not have the refrigerator technology required to maintain such low temperatures.
Because of this, the Oxford vaccine – which can be stored at between 2C and 8C – is expected to be easier to administer in the community and therefore provide the bedrock of the UK’s vaccination programme.
The latter technology platform is more stable, meaning it does not need to be stored and transported at below freezing, as is the case with the annual flu jab that is administered by GPs.
The Oxford University team is confident this will allow their vaccine to make more of an impact in the global market – once confirmation is provided of the jab’s effectiveness and safety.
Toby Peters, a professor of energy storage and cold economy at the University of Birmingham, said there was no need to be “completely focused” on the difficulties involved in the so-called vaccine cold chain.
“There are other fridge-stable vaccines coming along,” he told The Independent. “We know about the Oxford vaccine which is 2-8C, which will be better suited for wider population coverage, especially in the developing world.
“But that doesn’t change the need for a robust cold chain and doesn’t change the need for equitable distribution.”
Professor Jonathan Stoye, a virologist at the Francis Crick Institute, said there were “at least two drawbacks” to the Pfizer vaccine.
“First, it requires two injections for full effectiveness, spaced three to four weeks apart,” he said.
“Second, it needs to be stored at -80 degrees before use. Both properties will severely complicate administering the vaccine to many recipients, particularly in countries which are warm and have less developed cold chains.
“There is therefore every reason to continue the search for novel vaccines, particularly those requiring only one dose, which can be distributed in powder form and reconstituted prior to use.”
Health secretary Matt Hancock has meanwhile warned that mass distribution of the Pfizer vaccine would be a “colossal exercise” – one that involves “enormous complexity”.
The cost of rolling out the Pfizer vaccine is also expected to be at least 10 times higher than Oxford’s – though the government has not yet disclosed full details of its deals with the two groups.
Two doses of the US and German jab cost £29.47 for Americans, with the UK purchasing 40 million doses.
In contrast, the EU deal for the Oxford vaccine has been priced at £2.23 per dose. The UK has pre-ordered 100 million shots of this candidate.
Professor Robin Shattock, who is leading the development of the Imperial College London vaccine, said the UK needs “a toolbox as full as possible” of different vaccines for the months ahead.
He said a wide range of jabs would be required as some may work better in different age groups or among those with underlying health conditions.
He said he is “really hopeful” the Oxford University and AstraZeneca vaccine will report its results soon, with others following shortly afterwards.
“The AstraZeneca/Oxford vaccine, we anticipate that there may be a result anytime soon, before Christmas,” he told BBC Breakfast.
