Parvo and the vaccine has been around for a long time. It’s irresponsible pet owners who are causing the uptick in reporting.
Take a look at the vaxxes now offered for Parvo.
The only thing owners may be guilty of is ignorance.
Something else to consider.
Fomites are a means of transmission for Parvo.
Wonder if any of the outbreaks are nosocomial, cases picked up at the vet.
Especially with veterinary chains buying up so many practices, my bet is that to control costs, infection control gets short shrift.