[marktwain]

Many of the early vaccines (pre-1910) were not tested well and at least one caused more deaths than it cured.

The Covid vaccines were not tested to anywhere near the standard used just a few years before.

[DugwayDuke]

marktwain wrote: “The Covid vaccines were not tested to anywhere near the standard used just a few years before.”

They were tested to the same standards. The difference was instead of doing thing serially, things were done in parallel which reduced the time required. Simply good product management.