Almost half of Americans believe that the H1N1 swine flu outbreak has passed, and only one-third remain “somewhat” or “very” concerned about catching the virus, reflecting a significant reduction in levels of concern about the pandemic compared to last fall.

The Harvard School of Public Health poll is the latest in a series of nationwide surveys administered since last April by the Harvard Opinion Research Program to gauge the public’s attitudes and responses to the outbreak.

The poll also revealed that fears about vaccine shortages have mostly abated, as 70 percent of adults surveyed now believe there are adequate vaccine supplies in their communities. A poll last November had found that only 21 percent believed their communities were sufficiently prepared.

One of the survey’s most significant findings is that almost half of the parents polled do not intend to get their children vaccinated, according to Gillian K. SteelFisher, a HSPH researcher and the assistant director of the research program. The main reason cited by the parents concerned the vaccine’s safety, which points to the challenges in communication between the public and health officials, SteelFisher noted.

“There’s no shortage of vaccines anymore, but the people who aren’t getting the vaccines may have concerns that weren’t addressed by these outreach efforts,” SteelFisher said.

Though the poll shows waning public concern about getting sick, Stephen C. Redd, director of the Influenza Coordination Unit for the Centers for Disease Control and Prevention, cautioned against complacency.

“Rates of H1N1 disease are lower than they were in October and November, but the virus is still circulating and many people remain susceptible to disease,” Redd wrote in an e-mailed statement. “People who are not vaccinated should get vaccinated.”

According to University Health Services Director David S. Rosenthal ’59, the responses to the nationwide poll mirror those within the Harvard community.

“I think that a lot of people are fatigued of H1N1,” Rosenthal said, noting that while UHS had experienced a rush of individuals seeking the vaccine from November to January—when over 5,000 shots were administered—only about 50 students a day have shown up at recent clinics.

The drop-off in fear has accompanied an enormous reduction in cases of influenza-like symptoms among students. While UHS treated 900 such cases in the fall of 2009, there have been only 13 since Jan. 1.

“On the professional side, we are hoping that [H1N1] can be put on the back burner,” Rosenthal said, though he echoed Redd in advising continued vigilance and personal hygiene.

According to SteelFisher, the research group intends to continue tracking the evolution of the public’s response as the nature of the illness becomes clearer.

“It’s important to see what people think retrospectively [about the H1N1 outbreak] and what the implications are for moving forward,” SteelFisher said.

—Staff writer Evan T.R. Rosenman can be reached at erosenm@fas.harvard.edu.

—Staff writer Helen X. Yang can be reached at hxyang@fas.harvard.edu.