A little more than half of the Americans who were vaccinated from the flu last winter avoided infection. A new vaccine aims to give that effectiveness rate a booster shot.
On the heels of a difficult flu season, health officials this month began their annual vaccination push - in the process, touting a vaccine that protects against four strains of the virus, rather than three.
Last winter, Colorado suffered one of its worst flu seasons in a decade when 1,530 people were hospitalized, according to the Colorado Department of Health and Environment. Not since the 2009-2010 flu season - which featured the H1N1 flu pandemic - did health officials tally more flu hospitalizations across the state.
Last year in El Paso County, 161 needed to be checked into a hospital due to the virus, the department said.
The H3N2 virus proved particularly severe against those 65 and older in Colorado, while an influenza B strain caused an uptick in child hospitalizations, said Rachel Herlihy, the state's deputy director for disease control and environmental epidemiology.
Those age groups typically fare worse during flu season, said Bill Letson, El Paso County's medical director. But health officials stress that everyone 6 months and older should get a shot - due to the fact that anyone who's sick, regardless of age, poses a threat to infants or the elderly.
"Everybody in between, it makes sense to get immunized as well, mostly because of the way the virus gets moved around the community," Letson said.
Myriad factors play into whether vaccines work each year among different age groups. Chief of these lies in the fact that the virus strains placed in vaccines are different every year. As the virus evolves, researchers must predict how the strain will adapt from the previous version, and cater the vaccine to fit each evolution.
"There's a huge amount of fairly sophisticated and educated guesswork that goes into this," Letson said.
During the 2012-2013 flu season, the vaccine had a 56 percent overall effectiveness rate from Dec. 3 to Jan. 19, which roughly coincided with the virus's peak, according to the Centers for Disease Control and Prevention. But the effectiveness rate varied greatly among age groups.
About 20 percent of the vaccinations available in the U.S. feature the new, beefed-up vaccine, Herlihy said.
Also new this year: A vaccine made without first growing the virus in chicken eggs, a major advance for those who decided against flu shots due to allergies.
Doctors say there's no excuse for people who are afraid of needles as a nasal mist is available. All nasal mist vaccines carry the four-strain version, called the quadrivalent flu shot, Herlihy said.
There's also a shot available that involves a smaller needle - one that only pierces the skin, without digging into the muscle.
Even with all this preparation, however, it's anyone's guess as to whether this flu season is any better or worse than last season.
"It's really hard to say whether or not we'll see that same picture this year," Herlihy said. "We never really know."
TO GET A FLU SHOT
- Visit vaccine.healthmap.org for a searchable database that lists flu shot clinics by Zip code.
- Visit elpasocountyhealth.org to learn more about the flu, or to find flu shot clinics.
- El Paso County Public Health offers flu shots, with prices varying depending on health care coverage. To make an appointment, call 578-3199
STATE RATES FOR
2012-2013 flu season
All ages: 48.3 percent
Younger than 18: 58.4 percent
18 and older: 45.2 percent
65 and older: 72.1 percent
COLORADO DEPARTMENT OF PUBLIC HEALTH AND