By Katherine Mangan

The U.S. secretary of education, Arne Duncan, urged college students on Thursday to take advantage of their campuses' sporadic shipments of H1N1 vaccine before the holidays, adding that while the number of cases of the flu may be declining, "we're simply not out of the woods yet."

"If you're too bogged down with finals or too busy, we'd strongly encourage you to get vaccinated as soon as you get home," he said during a conference call with college-newspaper reporters. "While we've seen a dip in the number of cases reported nationwide, that could change at any time."

As of last week, 84 percent of the 220 campuses participating in a survey by the American College Health Association had received vaccine shipments. However, those deliveries were erratic and fell far short of meeting demand for the vaccine, according to James C. Turner, president of the college-health association and executive director of the University of Virginia's student-health department.

So far, colleges in the survey have administered 143,045 doses of vaccine, reaching 5 percent of their student populations, said Dr. Turner. He said he expected another wave of H1N1 cases to hit in January.

"The biggest problem is that campuses are getting 200 or 300 doses of vaccine at a time, and we don't know from one week to the next if we'll have enough on hand to arrange for 10 to 20 nurses, set aside a large area for a clinic, and notify students," he said.

The association has logged more than 85,000 cases of flu since late August out of a reporting population of nearly three million students. Three students have died and 161 have been hospitalized, but most cases have been moderate.

All but one state reported significant declines in flu cases last week, but because it fell over Thanksgiving break, the drop was difficult to interpret.

College students are among the highest-risk groups for contracting H1N1, often called swine flu, because they have lower immunity to it and live, eat, and socialize in close proximity to other students, health officials say.

Mr. Duncan also reiterated precautions about staying home when sick, letting a resident adviser know so ill students can be segregated if possible, practicing good hygiene, and frequently using hand sanitizers.