With encouraging signs that the H1N1 virus may not be as dangerous as first believed, Richard E. Besser, acting director of the Centers for Disease Control and Prevention, said foundations and philanthropists helped the agency prepare for a potential pandemic.

“Foundations play a critical role during emergencies,” Dr. Besser, a pediatrician, told members of the Council on Foundations.

For example, in 2001, as the agency, in Atlanta, worked frantically to trace the anthrax attacks on journalists and members of Congress, it set up a make-shift emergency-response center in an auditorium.

Bernard Marcus, the co-founder of Home Depot and a board member of the CDC Foundation, a nonprofit group that helps the agency, visited the somewhat jury-rigged facility and began raising money for a state-of-the-art operations center to monitor health emergencies. Mr. Marcus’s foundation also gave $2-million to help build it.

What’s more, Dr. Besser said, the Robert Wood Johnson Foundation, in Princeton, N.J., has helped to organize summits between government, business, and nonprofit officials to discuss how America should response to a disease pandemic.

“Those summits are the reason I believe we can respond efficiently” to outbreaks like the swine flu, Dr. Besser said.