How sophisticated mRNA vaccines from Pfizer, Moderna are and how they work?

Pfizer-BioNTech vaccine candidate, BNT162b2, was 90% effective in preventing infection during the phase 3 clinical trial, which enrolled 43,538 participants, with 30% in U.S. and 42% abroad

As the weather cools, the number of infections of the COVID-19 pandemic are rising sharply. Hamstrung by pandemic fatigue, economic constraints and political discord, public health officials have struggled to control the surging pandemic. But now, a rush of interim analyses from pharmaceutical companies Moderna and Pfizer/BioNTech have spurred optimism that a novel type of vaccine made from messenger RNA, known as mRNA, can offer high levels of protection by preventing COVID-19 among people who are vaccinated.

Although unpublished, these preliminary reports have exceeded the expectations of many vaccine experts, including mine.