Sonja Isger / Cox Newspapers

The flu season has gotten off to a late start, allowing people more time to get the annual vaccine before the season’s inevitable peak.

But the nation’s health authorities and a few scientists in the forefront of vaccine technology say we could be just a year from human trials of a “universal flu shot” that would make the annually reformulated ones obsolete.

Ideally, this universal shot would catch all previous versions of the flu virus, as well as future mutations.

It would take the guesswork out of calculating the shot Americans are urged to get every winter — averting missteps like the one that left the public vulnerable to the swine flu pandemic of 2009-10 that affected as many as 89 million people.

If trials continue to go as they have at Inovio Pharmaceuticals, officials there say a shot could be available in five years.

Even if those trials fail, national vaccine experts such as Dr. Gary Nabel at the National Institutes of Health are hopeful that scientists will succeed in making a shot that works before the decade is out.

“If you went back five years, you would’ve said then, ‘How would we ever get there from where we are?’ Now we’re all more optimistic, whether it be Inovio or someone else that succeeds,” said Nabel, director of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases.

What changed? Technology, and our understanding of how we can neutralize viruses, scientists say.

Shots involve guess work

Until now, doctors have tackled the flu with methods that date back at least 50 years.

Vaccines deliver a decoy, in this case a dead or weakened version of the influenza virus, to stimulate a person’s immune system. In other words: Attack what looks like this.

But the flu virus is a master at defense, dressing itself with an outer envelope that can mutate in months. And there are thousands of varieties of influenza, so health authorities each year pick a few they think are most likely to cause the most problems.

But when they don’t, the consequences are dire.

“We all saw what happened in 2009 with the H1N1 (swine flu) outbreak,” the NIH’s Nabel said. “There’s a great example of where we were all preparing for one type of seasonal flu, and something came in and it was a complete wild card.”

“We were caught flat-footed,” he added. “There were deaths that could’ve been prevented if we had a universal vaccine.”

The U.S. Centers for Disease Control and Prevention estimates between 8,870 and 18,300 Americans died of swine flu-related causes from April 2009 to April 2010.

Later, milder season here

This season has been mild. It didn’t officially start until late February, making this the latest flu season start in 25 years, according to the CDC.

So far, the flu viruses that are making the rounds are well-matched to the ones the CDC and the World Health Organization anticipated, said CDC spokesman Tom Skinner.

It has been a mild season for a couple of reasons, Skinner said.

One is the unseasonably mild weather — not the cold, dry climate in which flu viruses thrive. Plus, more folks were vaccinated as of November, and the strains circulating this year are similar to those of last year — so as a whole the population has a better immunity.