The federal government says it's a record-fast turnaround time from the first outbreak of the swine flu until Tuesday, when the first swine flu inoculations have became available.
The government and experts are warning: We're in for a long road this flu season, and there will be bumps along the way.
At hospitals in Memphis and Indianapolis, the first vaccinations for swine flu outside of clinical trials were given. The doses were FluMist, the nasal spray. Shots and FluMist will follow throughout the fall across the country.
"This vaccination is safe. It is not an experimental vaccine," said Dr Virginia Caine, Marion County, Indiana Health Department.
Today's first 5000 doses at each hospital went for health care workers and first responders.
Nurse Holly Smith was first in line at LeBonheur Children's Medical Center in Memphis.
"I think it's very important," she said.
But officials acknowledge that it will be many months before there are enough doses of vaccine to cover significant segments of the population. Distribution -- for both the swine and seasonal flu -- is difficult for many reasons, as CDC officials acknowledge.
"Is it fast enough? No. But it's what's feasible, it's what can be done," said Dr Jay Butler, CDC.
A big problem is lack of trained people to deliver the vaccines.
"The workforces in both the health care and public health are extremely stretched. We've let go many workers in both areas," said Dr Michael Osterholm, University of Minnesota.
Many people will be wanting vaccine and not getting it for weeks or even months. Polls show increasing number of Americans do not want the swine flu vaccine because of fears about its safety, even though federal officials have said there is no cause for concern.
"I think these two very different views are actually going to collide in the middle," said Dr Osterholm.
Meanwhile, the latest figures show that about a thousand people are now being hospitalised and about a hundred are dying every week from swine flu.