- Over 300 vaccines are in development with around 40 already in clinical trials.
- There are no vaccines approved yet in the UK, however the MHRA may approve a “temporary authorisation”. This will allow a vaccine for emergency use provided phase 3 clinical trial results are positive. This approval can be facilitated under 174 of the Human Medicines Regulations.
- The EMS has started a rolling review of clinical trial results to try to speed up assessments.
- Phases 1 and 2, and Phases 3 and 4 of clinical trials are being combined to help speed up the process.
- Phase 3 clinical trials often fail as the doses tested may produce a safety profile which is too high risk, alternatively the trial may highlight previously unapparent side effects.
- Both Russia and China have approved the use of a vaccine prior to the phase 3 trials have been undertaken.
- The UK has elected to take a portfolio approach to spread the risk of putting all their eggs in the one basket. This allows monitoring the development of vaccines with different modes of action. The UK has funded
- two adenoviral vector vaccines
- an mRNA vaccine
- an inactivated whole virus vaccine
- two adjuvant vaccines
- In addition, the UK helped to fund a RNA vaccine being devolved by Imperial College London.
- Four of the six vaccines being backed by the UK are already in phase 3 clinical trials and results are promising.
- There is evidence to suggest that one mode of action of vaccine may not work with all ages or sectors of the population. The older population are more susceptible to Covid-19 and they are less likely to mount an immune response to a vaccine.
- Flu vaccines are only 40% effective normally and the WHO has stated that they would like to see the target efficacy be at least 50% (preferrably 70%). It is not yet clear how long the protection will last with the vaccine nor if the booster should be the same type of vaccine or one with a different mode of action.