The flu vaccine did a poor job protecting older Americans against the illness last winter, even though the vaccine was well-matched to the flu bugs going around.

U.S. health officials on Wednesday released new vaccine data showing it did a so-so job overall.

The vaccine was about 42 percent effective in preventing illness severe enough to send a patient to the doctor’s office. But it was essentially ineffective protecting some age groups. That includes people 65 and older — the group that’s hardest hit by flu, suffering the most deaths and hospitalizations.

The flu season that just ended was a long one that peaked in February and was considered moderately severe. But the flu-related hospitalization rate for older adults was the highest it’s been since the severe 2014-2015 flu season.

Like that season, last winter was dominated by a kind of flu strain — Type A H3N2 — that tends to cause more deaths and serious illnesses than other seasonal flu viruses.

The CDC calculates vaccine effectiveness from a sample of flu tests done on patients in five states.

Vaccines against some other infectious diseases are not considered successful unless they are at least 90 percent effective. But flu is particularly challenging. Over the last ten winters, overall flu vaccine effectiveness has averaged about 46 percent.

Last winter’s vaccine did well in protecting young children, about 60 percent effective. And it did OK in older children and in adults ages 50 to 64. But it had no clear effect in adults 18 to 49, or among the oldest adults.

  • McGannahan Skyjellyfetti

    I doubt that it was effective for anyone of any age.

  • Disqus-helpsGOVTbreaklaws&kill

    big pharma made huge profits…so the complete failure was a success…