NEW YORK (AP) — The number of U.S. fatal overdoses fell last year, according to Centers for Disease Control and Prevention data posted Wednesday.

Agency officials noted the data is provisional and could change after more analysis, but that they still expect a drop when the final counts are in. It would be only the second annual decline since the current national drug death epidemic began more than three decades ago.

Experts reacted cautiously. One described the decline as relatively small, and said it should be thought more as part of a leveling off than a decrease. Another noted that the last time a decline occurred — in 2018 — drug deaths shot up in the years that followed.

“Any decline is encouraging,” said Brandon Marshall, a Brown University researcher who studies overdose trends. “But I think it’s certainly premature to celebrate or to draw any large-scale conclusions about where we may be headed long-term with this crisis.”