The final clinic, in downtown Sacramento, marks an end to one of the most extensive immunization campaigns the region has seen.

In mid-November, Sacramento became the area's first jurisdiction to provide nasal sprays and shots to high-risk populations. A couple of weeks later, when Sacramento opened clinic doors to everybody, it was one of the first counties in the nation to do so.

"Yes, it has been extremely challenging," said Sacramento's public health officer, Dr. Glennah Trochet. "This has been one of the hardest things we have ever done."

A cadre of county employees and volunteers set up vaccine assembly lines at schools, churches – anywhere that could hold a few thousand people. Wearing color-coded vests, they injected arms or sprayed noses, at a clip of about 500 per hour.

For the first clinic, more than 5,000 people waited several hours. The line snaked through the back parking lot and football field of Hiram Johnson High School. Several people in line scuffled as some non-high-risk people slipped through the initial screening process.

After the first week's tension, the clinics stopped turning people away, Trochet said.

"Most of the clinics were able to serve everybody who came," she said. "It's hard to characterize the turnout for the clinics, because it depended on the time or weather or location."

But noticeably fewer people have shown up to more recent clinics, Trochet said.

The last clinics coincide with a fall-off in swine flu cases regionally and in California.

Thursday, the state Public Health Department downgraded the novel H1N1 flu to "local" activity, meaning outbreaks and increases in new cases are limited to the Riverside and San Bernardino County area.

No H1N1-related deaths were reported in the state last week, said state epidemiologist Dr. Gil Chavez.

This doesn't mean the vaccine campaign is over, public health officials are saying.

"It's still not too late to get vaccinated, and even though we've seen a decrease in hospitalizations and deaths, there could be another wave of H1N1," Trochet said.

Public health officials worry the recent decrease in infections may lull the public into a false sense of security.

"The question is whether we will have a third wave," Chavez said. "Nobody knows the answer to that. In previous pandemics, there's always been a third wave."

The best way to stop a third wave is by continuing to press for the vaccination of as many people as possible, he said.

Other area counties are running clinics through the end of January. Yolo County's clinics continue through next week and Placer's continue for another two weeks.

Sacramento County is looking for a permanent location to continue administering the vaccine, Trochet said.

But things won't be nearly as crazy.

The Public Health Division's next step is to take a breather. Trochet said she's been so busy she hasn't evaluated the vaccine clinics.

"Haven't had a chance to think about that," she said.