It's been a tough year for the flu

We've been pretty lucky in the past few years.

That's why this year's flu season seems so bad. It's the worst doctors have seen in recent years -- though it's hardly one for the record books.

A few unusual twists add to the current misery, such as a less-than-ideal vaccine match and resistance to some antiviral drugs.

It's impossible to predict the nature of a flu season from year to year, doctors say, because its timing and severity depend on many factors, including circulating viruses and how well those match the ones in the vaccine.

This year's match wasn't great, experts say.

Each year, health-care providers create a vaccine based on their best predictions of what strains will become widespread. Those picks are made many months in advance so the vaccine can be produced and delivered on time.

In 16 of the past 19 years, the match between the vaccine and the strains that emerge has been "very close," said Curtis Allen, spokesman with the Centers for Disease Control and Prevention in Atlanta.

But influenza viruses are constantly changing and mutating. This year, only about 40 percent of flu strains circulating are covered by the vaccine, he said. In recent years, that number has been around 75 percent to 90 percent, he said.

"It's like forecasting the weather," Allen said. "People tend to remember when you're wrong."

If you put this season into a broader historical picture, it isn't anything for the record books, CDC officials say. Flu season normally peaks around now. It is now widespread in every state except Florida.

Doctors this year also have noticed resistance to a common antiviral medication, Tamiflu, though it's still being used to treat and prevent flu. But CDC officials have recommended against using other antiviral drugs amantadine and rimantadine because of resistance.

The Illinois Department of Public Health recently issued an alert to health-care providers after 10 Chicago-area patients tested positive for an influenza strain that was resistant to Tamiflu.

"This is not the worst season in number of flu cases," said John Saran, an internal medicine physician with Edward Medical Group in Naperville. "But it is more serious in terms of the vaccine and Tamiflu resistance, resulting in more complications like hospitalization for secondary bacterial pneumonia."

The flu vaccine still remains your best bet for protection, even with spring around the corner. That's because it can provide partial protection, shorten illness duration and lessen chances of flu-related complications, Saran said.

Just recently, a CDC advisory committee advised flu vaccinations for all school-age children. It now recommends that all children ages 6 months through 18 years get a flu shot, along with those who are 50 or older, have chronic health problems, or live in group settings.

Even though most kids can recover quickly from the flu, they still are "vectors of transmission," Saran said, bringing the virus home from school or day care.