Now this is hot off the press. It is nearly tomorrow in the UK so this Lancet publication is dated April 18, 2020.
Thanks for the news about Sarah Gilbert at Oxford. She's got the recombinant DNA vaccine approach covered. Not too surprised that the recombinant virus was getting pre-clinical testing at Porton Down, where they probably have the best available Level 4 isolation facilities as well as the best security.
Gilbert's early vaccine work … look[ing] at creating vaccine candidates that could trigger favourable T-cell responses, rather than relying solely on antibody responses … is critical. There must be a CD4 killer T-cell response that directly kills human host cells infected by the virus. This is like the Salk polio vaccine (worked only by an antibody response) vs. the more effective Sabin vaccine (worked by both antibody and T-cell responses).
If she has early progress, that £2·2 million grant will require more funding, hopefully from a Big Pharma company with deeper pockets.
Scaling up the manufacturing process is critical, and that appears to be going on in parallel with separate funding.
Gilbert … hopes to have vaccinated 500 volunteers by mid-May; this will be followed by an extension of the maximum age of trial volunteers from 55 to 70 years, later moving on to the over-70 age group. This age group, >55 years old, is often tested in later clinical trials. Better to get started on that age group right away. The trial with 500 volunteers can be considered as similar to what the FDA calls a Phase 2 clinical trial in the US. It will probably be given an interim analysis for efficacy, and if those results are good enough, enrollment will be expanded.
Phase 3 expansion is expected to involve 5,000 volunteers; results from the earlier [smaller] trials will be included in the efficacy follow-up. I wasn't far off when I said a Phase 3 trial would be in the range of 1,000 to 10,000 volunteers. This many vaccinations depends heavily on the success of the parallel manufacturing scale-up efforts.
“The best-case scenario is that by the autumn of 2020, we have an efficacy result from phase 3 and the ability to manufacture large amounts of the vaccine, but these best-case time frames are highly ambitious and subject to change”, Gilbert says. I wish her the best possible luck in her trials. It will be high pressure on all involved.
Of course, that kind of luck also means there will still be considerable levels of SARS-CoV-2 infection in the UK between over the summer. That also means no one in the UK is considering deliberately exposing anyone to live virus as a challenge to the vaccination. Trials elsewhere in the world, Europe, Asia, Africa, North & South America, and Australia are essential, both to test for efficacy among different human populations, and to ensure that somewhere still has active virus infections going on.
