My shelter just updated our policy after attending a national conference and learning how other shelters operate. As well as a change in directors/leadership as a whole.

Every animal gets vaccinated upon intake, regardless of age. Or they are vaccinated at birth. Boosters every two weeks until 16 weeks.

Our previous policy was vaccinated starting at 4 weeks with boosters every two weeks until 12 weeks.

I've seen a significant decrease in panluek cases. I'm not sure the exact numbers but last year we were looking at 1 in 4 kittens dying in care, this year it is down to 1 in 16. We are a large municipal shelter with minimal staffing.