THREAD

How were the first #CovidVaccines developed in less than a year without cutting corners?

The vast majority of vaccine development time is spent *preparing for* Phase 3: the final large-scale, costly, (usually) long trials to show a vaccine works and is safe. 1/

Those years are spent:
Confirming safety & immune response in small trials;
Optimizing the vaccine dose, schedule and trial endpoints; and
Demonstrating the vaccine can be manufactured in large volumes with high quality 2/

The first #CovidVaccines benefited from research done on SARS and MERS since the 2000s. Barney Graham’s lab at NIH played a key role in designing the mRNA construct, and a lot of work on the platforms was done by companies. 3/

@Carolynyjohnson https://www.washingtonpost.com/health/2020/12/06/covid-vaccine-messenger-rna/

Just being ready for a Phase 3 trial means most of the safety & efficacy risk has been resolved. In fact, vaccines entering Phase 3 have ~80%+ likelihood of being licensed. In that way, the Phase 3 COVID vaccines were similar to any other vaccines when they entered Phase 3. 4/

The Phase 3 trials themselves are very similar to standard vaccine Phase 3 trials, in terms of the size, how they’re designed, and the data they’re generating. Multiple spike-protein-based vaccines are in Phase 3, which will reinforce confidence in the safety of that target. 5/

COVID vaccine trials are accumulating cases much faster than a typical Phase 3 clinical trial, because they are being conducted in places with a lot of virus transmission. This allows vaccine efficacy (vs placebo) to be shown very quickly. 6/

There are some things we won’t know when vaccines are first authorized, such as duration of protection and potential for rare long-term safety issues. Transparency in the safety & efficacy data that is collected over time will be important for confidence in COVID vaccines. 7/

So we will have most of the safety & efficacy data we expect for other vaccines at the time of the first authorizations (EUA) and certainly first approvals of COVID vaccines. That, along with ongoing transparency, should be reassuring for everyone considering vaccination. 8/

Thanks to my colleagues Drs. Hansi Dean & Gary Dubin for their input to this thread! 9/