Q&A: Weighing the value of less effective flu shot

The Associated Press Published:


The vaccine was much better at protecting younger people.




A: It offered "moderate" protection, the CDC says. For all ages who were vaccinated, there was a 56 percent chance of avoiding getting sick with the flu from any of the three strains in circulation. Generally a flu vaccine is considered pretty good if it's more than 60 percent effective.

Q: Why didn't the vaccine do a better job this year?

A: Scientists don't know. But it is much harder to make an effective vaccine against ever-shifting flu viruses than for diseases like measles, polio and diphtheria. Vaccines are generally 90 to 95 percent effective for those other diseases.

Q: Why was the shot especially weak at protecting older people?

A: Older, worn-out immune systems have a harder time responding to flu vaccines. Protection for those over 65 is considered good if they have a 30 or 40 percent lower chance of getting sick enough to see the doctor. This year, the vaccine provided about 27 percent protection against all three strains -- but again, for the most dominant virus it was only 9 percent effective. On the upside, for people in their 50s and early 60s, protection against the worst virus was actually 50 percent.

Q: Can't we make a better vaccine?

A: Researchers are working on it. There is a higher-dose version for older people, but it's not clear how widely available it was and the study of vaccine effectiveness was too small to show whether it made a difference.



CDC flu page: http://www.cdc.gov/flu/

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