You may find this interesting if you are willing to learn a bit of history and how vaccines began and were tested. They did not have the tech back them they made it and prayed it worked. And it only had about a 50 -70 percent success rate at the beginning. So thank God you live in modern times able to make things much better. https://www.history.com/this-day-in-history/children-receive-first-polio-vaccine
