It also remains unknown who will fill the surgeon general post now that Dr. Sanjay Gupta, Obama's unofficial pick for the job, also withdrew from consideration.
Still, some said that while there's no doubt it would be best to have leaders in place, there is nonetheless a road map in place in case problems like this one arise.
At George Mason University, public policy professor James Pfiffner told ABC News career employees just below the top tier are well-equipped to confront swine flu and "have the expertise to do this."
Pfiffner also said he thinks there could be a plus side to the high-level vacancies because without political appointees in place to lead HHS and CDC, "the link between the (president) and the career people is short."
"I'm not really concerned about the fact that those three positions are open at this point," said ABC News' medical consultant Dr. Tim Johnson, adding that federal health officials are coordinating their response according to policies already on the books.
"I think they are rudderless in terms of making policy, dealing with the political issues that surround them, including health care reform," Johnson said today. "I don't think that can be said about swine flu."
"The good news is since the SARS and avian flu episodes five years ago, our public health structure is in much better shape than it was then," Johnson later said.
Leavitt, too, admitted that, "Those spots are occupied at this moment by some very capable people.
"Again, the thing that distinguishes a pandemic is the duration and the breadth," he added. "This is not a sprint. It becomes a marathon response, and permanent leadership is necessary."
On Capitol Hill, lawmakers have swiftly scheduled hearings for later this week to assess swine flu developments and help determine what's next for federal response.
ABC News' Jake Tapper contributed to this report.