That Flu Shot Won't Protect You From Whooping Cough

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By Mary Duenwald

As coughing echoes through half-empty offices and classrooms in New York City and 29 states experiencing extraordinary levels of flu, many of the still healthy understandably wonder whether the vaccine they got last fall will protect them.

The answer is probably yes, because the 2012-13 vaccine appears to be a good match with the H3N2 strain of Influenza A virus that's infecting most sufferers this year.

A more troubling question is whether vaccinations against pertussis, aka whooping cough, are still working. And it's an important one, because the U.S. is also experiencing what looks to be the biggest reported outbreak of whooping cough in 50 years.

As of Nov. 21, every state except California had reported an increase in the bacterial infection over the past year, and most of them have seen at least a two- to three-fold rise.

Whooping cough is famously a problem for children. Of the 18 deaths in the U.S. in 2012, most occurred in infants under three months. The next-highest rates of illness occur in seven- to 10-year-olds and, to a lesser extent, in 13-to-14-year-olds. When the illness occurs in adults, it can seem so much like a mild cold, it more often than not goes undiagnosed, and people think they just have a harmless lingering cough.

It's not at all harmless, though. The coughing spreads the pertussis bacteria around. In fact, children with whooping cough usually get it through exposure to adults who don't know they're infected, James Cherry, a professor of pediatrics at University of California at Los Angeles told me.

Adding to the danger is the limited usefulness of the vaccine. Pertussis vaccines have never been as effective as those for other illnesses, but the new "acellular" kind in use since the 1990s (because the older "whole cell" kind caused fevers and convulsions in some children) is especially weak. A study last year at the Kaiser Permanente vaccine center found after receiving all five doses in the series, children saw their immunity fade by an average of 42 percent a year.

This degree of drop-off was surprising enough that doctors may now need to consider frequent boosters. Already they are working to ensure that all adults who have contact with babies get fresh shots. In the long run, obviously, what's needed is a better vaccine.

Meanwhile, adults who are not necessarily near children are well advised to get booster shots, too. In some of them, the illness can be quite severe.

More important, adults should get that lingering cough diagnosed -- and, until they know for sure it's not whooping cough, keep away from children.

(Mary Duenwald is a member of the Bloomberg View editorial board.)

Read more breaking commentary from Bloomberg View at the Ticker.

-0- Jan/10/2013 21:44 GMT