Maybe it's the snow that killed it.

Maybe we've done it ourselves by washing our hands and declining to shake other people's (potentially unwashed) hands. Whatever the reason, the Centers for Disease Control and Prevention reports sweeping declines "across all key indicators" of swine flu activity, from hospitalizations and doctor visits to flu-related deaths—but experts still caution that the danger isn't over.

Since the epidemic's outbreak in Mexico in April, H1N1 has killed between 2,500 and 6,000 Americans, the CDC estimates, and the New Mexico Department of Health reports 47 deaths statewide.

Though its numbers are dwarfed by the estimated 36,000 Americans who die annually of regular, seasonal flu—a disease that garners a lot less media attention—H1N1 still worries retired Los Alamos National Laboratory scientist and special SFR swine flu correspondent Douglas Roberts.

"There's still no way of knowing whether the virus will mutate, as it did in 1918," Roberts says. The H1N1 outbreak of 1918 was similar to this one, he notes, except it came back with a vengeance in 1919."The possibility exists that that will happen with this virus as well," Roberts says.

According to the Federation of American Scientists, the 1918-1919 pandemic killed between 20 and 50 million people. "Without vaccines, we'd see equivalent numbers of deaths now from a new, more virulent form," Roberts says.

That there are vaccines—albeit in short supply—hasn't done much to quell the occasional upwelling of global hysteria: In April, Egypt ordered the slaughter of tens of thousands of pigs to halt the spread of the (non-porcine) swine flu; in Asia, everyone started wearing masks—which wasn't all that weird; it was the masked people in the Albuquerque airport who looked oddly like bio-bandits. Tongue-in-cheek monikers like Aporkalypse and Snoutbreak circulated, and the always-good-for-a-gaffe Vice President Joe Biden told everyone to stay off the subways.

For all the hype, though, swine flu did have very real effects. New Mexico's hospitals filled up; many saw "increased visits from people [who] weren't even sick at all," state Epidemiologist C Mack Sewell says. According to Arturo Delgado, spokesman for Christus St. Vincent Regional Medical Center, cases of influenza-like illness have declined considerably both at Christus and surrounding clinics—from approximately 180 flu patients per day in October at the height of the pandemic, to a high of 28 patients in the first week of December.

"That's a really dramatic drop in the number of patients," Delgado says—but he notes, "That doesn't mean we're out of the woods."

Sewell agrees. On Dec. 10, the CDC reported that only 15 percent of Americans have been exposed to H1N1. That's dangerous, Sewell says, because the other 85 percent are still susceptible. "There's a lot more people that could get infected," he says. "That's one of the reasons we really want to keep pushing vaccinations."

But vaccinations have been a problem, too. After significant delays this fall, H1N1 vaccines have finally started trickling in to New Mexico—but still not in the numbers the state DOH had expected, Sewell says.

"It's been disappointing the rate at which the manufacturers have been able to produce vaccines," Sewell says. Though the 478,000 doses of nasal and injectable H1N1 vaccines the Department of Health has ordered are coming in steadily, Sewell says he doubts the DOH will be able to meet its January 2010 goal.

"Given some of the production delays, I would hesitate to say that we'd have 1.2 million [doses] by the first of the year," Sewell says. "I think we'll just have to wait and see."

But even as drug manufacturers struggle to catch up on orders for H1N1 vaccines, flu season is upon us: Delgado says it usually runs from December through February. And while H1N1 numbers are down, that doesn't mean it's not dangerous.

"One of the concerns is, when you have a new strain of influenza like this, we could conceivably have another peak next year," Sewell says. The H1N1 mortality rate among Native Americans and Alaska Natives is also four times that of the general population, he notes—a particular concern for New Mexico.

The bottom line? Keep washing those hands.