Good News, Bad News on Flu Season

Let’s pause for a moment of appreciation: We are having an incredibly light flu season.

Usually, this time of year, schools and offices are hard-hit with influenza. In a moderate or heavy year, schools report up to 30% absentee rates, while visits to doctors’ offices triple.

None of that has happened this year, and there are no signs that a flu wave is about to hit (although the East Coast has reported some sporadic outbreaks this month that could head west).

“It’s one of the mildest years in ages,” says Dr. Shirley Fannin, of the Los Angeles County Health Department’s Disease Control division. “What we’re seeing in the way of illness is not influenza. It’s more upper-respiratory illnesses.”

The flu season is mild because there are no new strains, and none of the circulating strains have mutated much. This means most of us have already been exposed to the existing viruses, Fannin says.

“The longer you go without having a totally new strain, the milder the influenza season gets. That’s because there will be lots of immunity throughout the world to the strains you’ve been seeing,” she says.

The bad news in this good news is that we are overdue for a whopping bad year. The last new influenza virus emerged in 1967. Historically, a new strain had appeared every 10 to 12 years.

“We’re now getting close to 30 years since we’ve had a brand new strain. That’s a bit bothersome because when changes occur, you don’t know if you’ll intensify some characteristic of the virus,” Fannin says.

Ten percent to 20% of the population contracts flu each year, causing about 20,000 deaths in the United States. The elderly and people with already weakened immune systems are most at risk for serious flu complications.

In a heavy year, the flu cases can stretch into April. But in mild years, it can fizzle out by the end of February.