This year’s flu shot is doing a startlingly dismal job of protecting senior citizens from the harshest strain this season, proving only 9 percent effective, the government said Thursday.
Health officials don’t know why this is so, but it helps explain why so many older people have been hospitalized with the flu this year.
Flu vaccine tends to protect younger people better than older ones and never works as well as other kinds of vaccines. But experts say the preliminary results for seniors are disappointing and highlight the urgent need for a better vaccine.
Overall, the vaccine’s effectiveness is a moderate 56 percent, which means those who got a shot have a 56-percent lower chance of winding up at in a doctor’s office with the flu. That is nearly as good as other flu seasons, the Centers for Disease Control and Prevention said Thursday.
For those 65 and older, it offers far less protection. It is 27 percent effective against the three strains in the vaccine, the lowest in about a decade but not far below from what’s expected. But the vaccine did a particularly poor job of protecting older people against the toughest flu bug, which is causing more than three-quarters of the illnesses this year. CDC officials say it’s not clear why.
Vaccinations are recommended for anyone over 6 months, and health officials stress that some vaccine protection is better than none at all. While it’s likely that older people who were vaccinated are still getting sick, many of them may be getting less severe symptoms.
“Year in and year out, the vaccine is the best protection we have,” and vaccinations are still recommended for senior citizens, said CDC flu expert Dr. Joseph Bresee.
To be sure, the preliminary data for seniors is less than definitive. It is based on fewer than 300 people scattered among five states.
But it will no doubt surprise many people that the effectiveness is that low, said Michael Osterholm, a University of Minnesota infectious disease expert who has tried to draw attention to the need for a more effective flu vaccine.
Older people have weaker immune systems that don’t respond as well to flu shots and are more vulnerable to the flu and its complications, including pneumonia.
Health officials at a meeting Thursday said they don’t know why this year’s vaccine did so poorly in that age group. One theory, as yet unproven, is that seniors’ immune systems were accustomed to strains from the last two years and had more trouble switching gears to handle this year’s different, harsh strain.
Among infectious diseases, flu is considered one of the nation’s leading killers. On average, about 24,000 Americans die each flu season, according to the CDC.
This flu season started in early December, a month earlier than usual, and peaked by the end of year. Hospitalization rates for people 65 and older have been some of the highest in a decade, at 146 per 100,000 people.