March, 2021. CNN breaks the news that the Pfizer vaccine is 100% effective.

Documenting the 21st century.
When scientists had not yet been replaced by body snatchers (see the 1978 movie) and one did not have to “believe in science,” it was clear to everyone that there is no scientifically valid result that can be said to be 100% certain. If, for example, you asked a physicist how certain it was that the sun would rise tomorrow, he would tell you that there was a reasonable probability of 99.9%. Things have definitely changed in the 21st century.