attached link explains. The article also goes on to explain all the details of why the CDC was so anxious to increase the percentage of the population were vaccinated, since in the early going it was only around 30%...we needed somewhere in the neighborhood of 70%+ to achieve "Herd Immunity" from COVID.
Once again, as we've all seen by now...getting vaccinated has always been the right path to take...even when the first use was only 95% effective.
Stop trying to excuse the Proven Liars around you by trying to find the relative 'pin head' of a mistake by people you see as 'Opponents', instead of Professionals doing their very best to keep you Healthy and Alive...or even Free from a deeply flawed 'Wannabe Hitler', as J.D. Vance would say.
Link: https://www.nytimes.com/2021/04/01/health/coronavirus-vaccine-walensky.html