"It's too early to say if the pattern will hold up, and these are very preliminary numbers and likely undercounted," said Jeff Lancashire, a spokesman at the National Center for Health Statistics. In Tennessee — one of the states hit hardest by the epidemic, but which saw a 12.3 percent drop in deaths between August 2016 and August 2017 — health officials said they, too, weren't sure whether those numbers would hold. Between August 2015 and August 2016, the state had 1,579 overdose deaths; in the 12 months that followed, it recorded 1,385. (The Nashville Tennesseean reported last summer that the state has undercounted drug deaths in the past.)