At Oxford, Prof Gilbert’s team is effectively trying to adapt a different virus, taken from chimpanzees, to do the job. At Imperial, Prof Shattock’s team plans to inject a harmless genetic recipe from Sars-Cov-2 into the body so that the body itself generates the spike proteins.
“We are essentially using nucleic acid, RNA, to deliver the code for the surface protein of the virus, and so we deliver that in, essentially, a liquid droplet,” Prof Shattock told the BBC. “The Oxford group are doing something similar, but are using a viral particle to deliver their genetic code to the cells following injection.”
That viral particle – chimpanzee adenovirus Oxford 1, or ChAdOx1 – has already been studied as a potential vaccine delivery mechanism against another coronavirus, Middle Eastern respiratory syndrome (Mers), which emerged in Saudi Arabia in 2012. Now it has been repurposed as ChAdOx1 nCoV-19.
A clinical trial will begin in the UK on Thursday to test its efficacy. In the test, 510 healthy adults between the ages of 18-55 will be split into five different groups and participate in the study for approximately six months, with the option to to have an extra follow-up visit after 12 months, in May 2021.
Two groups will receive a single dose of ChAdOx1 nCoV-19, containing 50 billion so-called “viral particles”. Two other control groups will instead receive a single dose of the MenACWY vaccine, which protects against four strains of the meningococcal bacteria – A, C, W and Y. None will know what they have been given.
The fifth group, meanwhile, will be given two doses of ChAdOx1 nCoV-19, one at the beginning of the trial and one after four weeks.
The trial has two very simple aims – does the vaccine work, and is it safe? – and will accordingly test for cases of Covd-19 after six months as well as monitoring so-called “serious adverse events”, or SAEs.
The Imperial study will not begin until June. But according to Matt Hancock, the Health Secretary, who this week announced £22.5 million of funding for Imperial and £20 million for Oxford, Government money would support clinical trials “to assess a sample of several thousand”, and for that to be followed by an even larger trial.
Getting to such human trials now has been the fruit of dramatically accelerated work given vaccines usually take up to 18 months to develop. The following info graphic shows the usual routes to treatments and the timescales involved.