The Shingrix vaccine is very effective at preventing shingles. It is recommended for people age 50 and older, even if you've had Zostavax vaccine or shingles.
People who have already received any shingles vaccination (Shingrix or Zostavax) have some protection against shingles.
Shingles is a two-dose vaccine, with recommended time between doses of 2 to 6 months, but increasing time between doses will not affect your long-term immunity.
For how to get Shingrix at UHS, see Immunizations.