By Serena Gordon
FRIDAY, Feb. 14, 2014 (HealthDay News) -- If you want to avoid the very worst of the flu, get a flu shot.
That simple message is hammered home in a new study from Duke University Medical Center that found virtually all of the people with influenza who ended up in intensive care earlier this flu season had chosen not to get the annual flu vaccine.
"Over and above the reduction in the number of flu cases for those who have been vaccinated, our study also seems to support a reduction in severe illness," said the study's senior author, Dr. Cameron Wolfe, an assistant professor of medicine in the division of infectious disease.
"You're far less likely to end up in intensive care if you've had the vaccine," Wolfe said.
What's more, the dominant strain of flu this season is the H1N1 strain, which tends to cause more severe illness in the young, Wolfe said. The average age of flu patients hospitalized at Duke this season was just shy of 29, according to the study, which was published online this week in the American Journal of Respiratory and Critical Care.
"Another take-home point is that flu can badly affect the health of young and otherwise healthy individuals," Wolfe said.
Flu is a highly contagious viral illness. The severity of the flu season varies from year to year. To avoid getting the virus, the U.S. Centers for Disease Control and Prevention recommends everyone 6 months of age and older gets a flu vaccine.
Vaccination rates for this year are low -- about 40 percent, according to background information in the study.
Wolfe and his colleagues wanted to capture a snapshot of the current flu season before it's over. Their study included cases of flu from Nov. 1 through Jan. 8.
Their medical center had 55 flu patients admitted during that time because of flu-related complications. Only 13 of those patients had been vaccinated against flu at least two weeks prior to their admission. (It takes at least two weeks for your body to build immunity to protect you from the flu).
Twenty-two of the patients required treatment in the ICU. Just two of those patients had been vaccinated against the flu, and they had other medical conditions that would prevent their bodies from effectively responding to the vaccine.
Of the 11 other vaccinated people who were hospitalized but not in intensive care, nine were immune-compromised in some way.
Wolfe said these findings show that even if the flu vaccine doesn't completely prevent you from getting the flu, it does offer "a protective effect against severe disease."
The researchers also found that about one-third of the flu cases admitted to intensive care had previously tested negative for the flu, suggesting that doctors shouldn't depend on flu tests alone when deciding whether to prescribe anti-viral medications.
Norbert Herzog, a professor in the department of medical sciences at the Frank H. Netter School of Medicine at Quinnipiac University in Hamden, Conn., said it's a shame that flu vaccination rates aren't higher. "Flu kills around 35,000 people a year, and about 200,000 a year end up in the hospital," he said.
Both experts said the flu vaccine is by far the best way to protect yourself against the flu.
"It's never too late to get vaccinated," Herzog said. "The flu circulates best in the colder months, but it can strike at any time. And people need to understand that just because they got the flu shot last year, doesn't mean they have immunity for this year. The strains change from year to year."
Other preventive steps include washing your hands or using hand sanitizer, and staying away from people who might have the flu.
Wolfe also noted that 10 percent to 15 percent of people will notice some muscle soreness and feel a bit unwell for a few days after getting a flu shot.
"That's the protective effect of the vaccine you're feeling," he said. "Your immune system is recognizing a virus and responding."