I guess back then doctors were nott rying to infect us with all kinds of crap and dangerous other substances found in modern vaccines like Mercury for example.
...the "purity" of the older vaccines is dubious at best. We probably don't know what was in them and neither do the people who made them. These days we have ways to measure "purity" superior to anything available earlier. As a result the purity of current vaccines is better than it has ever been.
Liberals are like a "Slinky". Totally useless, but somehow ya can't help but smile when you see one tumble down a flight of stairs!