Can someone provide the science

[LifesTooShortYOLO]

Behind MRNA vaccines?
Me and OH just having a debate where he says it's completely new they've never trialled it on anyone before and it's never been approved but I seem to think I read somewhere that it isn't actually a new way or making a vaccine? 🤯

AFAIK, mRNA vaccines have been trialled in humans (for rabies, and other coronaviruses like 'flu), but they have never been used routinely.

One of my sons said that they had been used before for cancer treatment.

publichealth.jhu.edu/2021/the-long-history-of-mrna-vaccines

Been around for decades, never been a commercial/public need until now is the TL:DR answer.