Today marked the start of Phase 3 RCT for @moderna_tx mRNA #COVID19 vaccine. Will enroll 30,000 volunteers across 87 locations. Half will receive two 100 microgram injections & half (control group) will receive a placebo. Both will receive the 2 injections about 4 weeks apart.(1)

Many are asking “when will we get results?” @NIH stated that it could have results as early as Nov. It is possible but unlikely. How fast we get results depends on several factors. (2)

Key among them is: how fast does the trial enroll its volunteers, what is the #COVID19 attack rate in the trial population, and, very importantly, how effective the vaccine truly is.(3)

The study is designed to detect a vaccine that is at least 60% effective in preventing #COVID19. In other words, the vaccine should reduce the disease attack rate by at least 60% when compared to the unvaccinated group.(4)

If there is a lot of #COVID19 circulating, and the vaccine is very effective, we could know as soon as November. The Data Safety Monitoring Board will take a peek at the data after a certain number of infections occur in the trial population.(5)

If there is a significant imbalance in the number of cases between the vaccinated and the control group, with many more cases occurring in the control group, they could stop the trial early.(6)

But even then it would take several months, at best, given the time it takes to enroll volunteers, the need for two doses 4 weeks apart, and the need for a certain number of infections to occur in the trial population to be able to compare the two groups.(7)

Once the trial ends, the @US_FDA will need to review the data carefully. If they give the go ahead, likely under an EUA, the available doses of vaccine will be distributed. It will be a complex task. And it will only count if people roll up their arms to be vaccinated.(8)

Safety monitoring will be essential, even after the trial ends. There will be many remaining questions. We will need to find out how long protection lasts. Let’s all hope for the best. In the meantime, let’s hold on to our face masks and keep up the physical distancing.(9)