Others may still be fuming about getting a flu shot but still getting the flu.
This year's vaccination is only effective against 40 percent of this season's influenza viruses, according to the U.S. Centers for Disease Control and Prevention, a stark contrast to the past. During most years, the vaccination is effective against 80 percent to 90 percent of flu bugs, according to Bennett Shenker, M.D., instructor and research fellow in the department of family and community medicine at Thomas Jefferson University in Philadelphia.
Flu vaccinations are created by experts who assess the strains of the flu from the season before, then make a prediction about which strains will circulate when the season comes around again. This year, that process didn't go so well.
"I think they've determined that there may have been some mutations that occurred and made the strains somewhat different from what they're expecting," said Shenker.
Usually, the predictions go well.
"In the last 19 years, they got it right 16 of the 19 times," said Stephen Sivak, M.D., the Paul J. Johnson chairman of medicine at Albert Einstein Medical Center, also in Philadelphia.
Sivak and Shenker agreed that they have seen an exceptionally high amount of flu cases this season, perhaps due to the less effective vaccine. "It's one of the worst seasons ever!" declared Sivak.
The flu was so bad this season that it even hit the cast of "American Idol" during the show's first live taping in February, forcing many contestants to sing even though they were sick.
So are you upset that you wasted time getting that flu shot and still got the virus? Are you telling everyone how smart you are for never getting that shot in the first place?
Not so fast, say doctors.
Even a flu shot that is not an exact match can still offer protection, explained Sivak, because the antibodies in the vaccine are still similar to the ones designed to treat a specific strain.
"You're less likely to get a complication," he said. "The illness will also be less severe."
Less-effective flu shots this year could affect people's opinions next year, according to Jerry Zuckerman, M.D., medical director for infection protection and control at Einstein.
"We'll recommend the influenza vaccination, and people will say, 'I got it last year, and it didn't work,' " said Zuckerman. "Now we have to go back and re-educate and say, 'Yeah, you got the flu. What would it be like if all these folks didn't get the shot? How severe would [it] have been this year?' "
Doctors recommend that anyone considered at high risk of developing complications from the flu -- defined as people with cancer, immune-deficiency disorders, or lung, heart, kidney or liver diseases -- should be vaccinated, regardless of age.
To prevent the virus, Sivak recommends being "diligent" about washing your hands and making sure to keep your fingers out of your nose or mouth.
If you do get the flu, doctors normally prescribe an anti-viral drug within the first 48 hours. If a high-risk patient comes in after that, it's still a good idea to take the medication, said Zuckerman. For healthy adults, it will not offer much benefit after two days, and patients should just let the virus run its course.
At that point, "it's bed rest and fluids," he said. "It's just kind of symptomatic care."
The Advisory Committee on Immunization Practices said recently that everyone between the ages of 6 months and 18 years should get a flu vaccination. Previous guidelines recommended the shot through age 5. The elderly should also consider getting shots.
Sivak claimed that the increase in age is because children are more likely to be in group environments like school, making it easier to spread the virus.
Zuckerman added that he thinks the advisory committee is not done yet: "I wouldn't be surprised in the next three to five years [if] annual influenza vaccinations will be recommended to all age groups and all people."
Shenker also warned that while winter may be winding down, flu season is still going strong. "It's reasonable to expect that we will be seeing cases of it for the next couple of weeks and into the spring," he said, noting that last year's flu season peaked on March 10 and lasted until May.