By Richard Knox
This flu season is shaping up to be a bad one. And this year’s vaccine doesn’t work very well against the most common flu virus going around. So should you even bother getting a flu shot?
Yes. Putting it a different way: My wife, my daughters and I will. And the evidence says you’d be somewhere between slightly foolish and dangerously blasé if you don’t — depending on your personal risk factors.
I know there are naysayers — the Internet is full of them. “I recommend that my patients of all ages not take these incessantly promoted immunizations, primarily because of their lack of effectiveness,” writes blogger Dr. John McDougall. He says he’s not one of those across-the-board vaccine deniers but just doesn’t think flu vaccines (of any given year) are worth taking.
To understand why I think he’s wrong — even this year, when vaccine effectiveness is expected to be even lower than usual — you need to know something about the situation we’re all in.
Several viruses circulate during any given flu season. And flu viruses are always changing — sometimes not so much from year to year; sometimes in a bunch of little ways (a phenomenon called genetic “drift”); and sometimes in a big, sudden way, called a “shift,” which touches off pandemics.
Drifts Or Shifts?
Public health researchers constantly monitor flu virus mutations. But even the smartest flu dudes can’t know in advance when they’ll happen, or whether mutations will be drifts or shifts.
This year, one of the flu viruses outwitted them. Or, since viruses can’t have intentions, it’s better to say that random genetic drift in that viral strain, called H3N2, happened in late March. That’s a bad time in the annual cycle of vaccine production.
Just a few weeks earlier, leading flu specialists gathered at the World Health Organization in Geneva and decided that this season’s vaccine (for the Northern Hemisphere) should contain the same viruses as last year’s — two type-A viruses (an H1N1 that caused the pandemic of 2009 and has stuck around since, and an H3N2 that first appeared in Texas two years ago) and two type-B flu viruses.
Making each year’s flu vaccine is a complicated business that waits on no virus. The recipe has to be decided in February to get the chosen viruses growing in hundreds of millions of special chicken eggs, the first step in vaccine production. Continue reading