CONCORD, N.H. (AP) — New Hampshire’s new vaccine registration system struggled to meet demand in its first big test Monday.

The state last week replaced a federally-run system with its own Vaccine and Immunization Network Interface, VINI for short. Thousands of people experienced problems with the previous system, particularly in scheduling their second doses, and officials had expected the new system to avoid those woes. But it was beset with technical problems Monday morning, when registration opened to anyone age 50 and older.

A message on the vaccine website says officials are working to address the issue and that registrations may still be processed, but at a slower pace.