This Year’s Flu Vaccine Is Worse than We Thought

iStock/Thinkstock(ATLANTA) — This year’s flu vaccine is only 23 percent effective against this year’s predominant strain, H3N2, according to a new report out Thursday from the Centers for Disease Control and Prevention.

In the middle of a bad flu season, it turns out the vaccine doesn’t offer much protection against the flu because the predominant strain has mutated since the vaccine was created and manufactured, according to the CDC.

“Scientists had to select strains for the vaccine back in February,” said Dr. Richard Besser, ABC News chief health and medical editor. “Between then and now the flu virus mutated significantly. Unfortunately, it is too late to make a change for this year. We are stuck with the vaccine we’ve got. CDC still recommends people get vaccinated since some protection is better than none.”

The shot is proving least effective for people from 18 to 49 years old, protecting them against only 12 percent of H3N2 viruses. Among people over 50 years old, the vaccine is protecting against 14 percent of the viruses, according to the new report.

But the vaccine offers children between 6 months and 17 years old 26 percent effectiveness. However, the age breakdowns are based on small samples and may change.

Besser explained that vaccines often work differently among different age groups because immune systems are “constantly changing” as people age.

“One of the reasons they developed a high dose flu vaccine for the elderly was because the elderly never respond as well as other age groups, and their risk of having severe flu is the greatest,” he said.

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