Besides that, mrna tech started to be developed in the 1970's with the first labrat trials in the late 80's or early 90's.

Clinical trials on humans, to test their safety and effectiveness in combating various diseases and viruses have been ongoing for the past decade.

And as you said, the first several widely used vaccines based on mrna tech have been deployed to literally billions of people.

This is an incredibly gigantic sample size for data and there have been very few issues for the past 3 years.

And what bernieecclestoned brings up about herd immunity simply means the people they are talking to are, like most antivaxxers, blithering idiots that know some catch phrases and not a single meaning behind them.

You obtain herd immunity through hardening the herd with vaccines and then hope the immune systems of the herd adjust to further combat the disease. If data doesn't show that new variants are easily countered by the immune systems of the herd, you know you need to develop more vaccines.