Most recent flu vaccine proving unusually ineffective

NEW YORK — The flu vaccine is doing a poor job protecting older Americans and others against the bug that’s causing most illnesses.

Figures released yesterday suggest the vaccine is 36 percent effective overall in preventing flu illness severe enough to send a patient to the doctor’s office.

There’s only been one other time in the past decade when the flu vaccine did a worse job.

Most illnesses this winter have been caused by a nasty kind of flu called Type A H3N2. The vaccine was only 25 percent effective against that type.

This kind of virus tends to cause more suffering and has been responsible for the worst recent flu seasons.

“The fact that the vaccine doesn’t work as well as we would like is clearly a contributing factor,” said Dr. William Schaffner, a Vanderbilt University vaccine expert.

The estimates were published by the Centers for Disease Control and Prevention.

The numbers are based on relatively small numbers of people and they are considered preliminary.

The effectiveness estimates come from the tracking of about 4,600 children and adult patients in five states. The vaccine provided good protection — 67 percent effective — against another common kind of flu virus, Type A H1N1, which has not been seen much this winter. And it was 42 percent effective against Type B flu viruses.

The vaccine worked relatively well in young children, but it performed worse in older people. Against H3N2, the vaccine was 51 percent effective in children ages 6 months to 8 years. In every other age group, the numbers were low, falling in a range that made them essentially ineffective in preventing flu, statistically speaking.