In medicine, as in life, nothing is perfect.
This is true of vaccines. No vaccine is 100% effective. Yet, vaccines have produced massive declines in many serious illnesses, and succeeded in eradicating two such illnesses (smallpox in humans and rinderpest in cattle).
Since COVID-19 has come along, everyone is talking about herd immunity. This is a straightforward idea. Let’s say I’ve never had smallpox. I’ve never been vaccinated against it. But, if you put me in a group of people who are immune to smallpox, I’ll never catch smallpox. Why? Because they can’t catch it to spread it to me.Continue reading