According to CNN medical correspondent-;Elizabeth Cohen's article;
Pfizer's and Moderna's vaccines have similar results because they use the same technique to activate the body's immune system.
Pfizer's ultra-cold vaccine, a 'very complex' distribution plan and an exploding head emoji
"The vaccines deliver messenger RNA, or mRNA, which is a genetic recipe for making the spikes that sit atop the coronavirus. Once injected, the body's immune system makes antibodies to the spikes. If a vaccinated person is later exposed to the coronavirus, those antibodies should stand at the ready to attack the virus.
No vaccine currently on the market uses mRNA.
"There has always been skepticism about mRNA -- it's brand new and would it work?" Fauci said. "What we saw in the trials is there was no real safety concern, and the efficacy is quite impressive. We saw nearly identical results [with Pfizer and Moderna] and it almost really validates the mRNA platform."