The CDC is reporting that flu season has peaked nationwide. We’ve still been seeing children with influenza symptoms (high fever, runny nose, bad cough, sore throat, body aches, headaches, etc) in the office over the last few weeks, but fewer than in December and January.

The predominant strain this flu season — Influenza A (H3N2) — was predicted to be particularly nasty, and nasty it was. By the end of January, the hospitalization rate for elderly Americans was at the highest rate ever recorded by the CDC.  By the second week of February, 80 children had already died of complications of influenza in the United States.

One reason for flu’s severity is the relative ineffectiveness of this season’s flu vaccine. After the vaccine was put into production early in 2014, the influenza virus “drifted” or mutated, making the vaccine only 23% effective in completely preventing the disease. (Usually, influenza vaccine is more than 60% effective in completely preventing the disease if exposed.)

23% effectiveness is not very good at all, but it’s better than 0%. Consider:  If you had a room filled with 100 people who received the vaccine, then exposed them to the influenza virus, 23 out of 100 would be completely protected and not get sick. Of the remaining 77 who were exposed, some (not all) of them would get sick. However, those who did could still get some cross-protection from the vaccine they received since there are some similarities to all flu strains. Indeed, this flu season we have seen a fair share of children who received influenza vaccine who ended up getting sick with influenza. A few got really sick and needed to be evaluated in the emergency department, with some needing to be admitted to the hospital. This unfortunately happens every year, but more so this season because of the less effective vaccine.

Even with the less effective 2014-2015 influenza vaccine, children who did receive it got influenza less frequently, less severely, required fewer expensive and nausea-inducing antiviral medications, fewer diarrhea-causing antibiotics, less radiation in chest X-Rays, and less exposure to other assorted nastiness in hospital emergency rooms and inpatient wards, than those children who did not.

23% is bad, but it’s better than it sounds. It’s much better than none.

Follow the Centers for Disease Control Weekly U.S. Influenza Surveillance Report here.

(Image: CDC)