Deaths in the current flu season have officially crossed the line into “epidemic” territory, federal health officials said Friday, adding that, on the bright side, there were also early signs that the caseloads could be peaking.

Officials from the Centers for Disease Control and Prevention, speaking on a telephone news conference, again urged Americans to keep getting flu shots. At the same time, they emphasized that the shots are not infallible: a preliminary study rated this year’s vaccine as 62 percent effective, even though it is a good match for the most worrisome virus circulating. That corresponds to a rating of “moderately” effective — the vaccine typically ranges from 50 percent to 70 percent effective, they said.

Even though deaths stepped — barely — into epidemic territory for the first time last Saturday, the C.D.C. officials expressed no alarm, and said it was possible that new flu infections were peaking in some parts of the country. “Most of the country is seeing a lot of flu and that may continue for weeks,” said Dr. Thomas R. Frieden, the C.D.C.’s director.

New outpatient cases — a measure based on what percentage of doctor visits were for colds or flu — dropped off slightly from the previous week, to 4 percent from 6 percent. The trend was more pronounced in the South, where this year’s season began.