You’ve heard it repeatedly: You should get your annual flu shot. You can go to your local pharmacy, doctor’s office, or hospital to get the shot, but you should probably know that there are two different types of shots, each of which offers varying coverage.
One is the trivalent vaccine, and the other, the quadrivalent vaccine. The trivalent vaccine protects against three strains of the flu — an influenza A, or H1N1, virus; an influenza A, or H3N2, virus; and an influenza B virus. The quadrivalent vaccine, meanwhile, protects against four strains: all of the strains in the trivalent vaccine, plus an additional B virus strain.
There is a type of quadrivalent flu shot that can be given to children as young as 6 months, according to the Centers for Disease Control and Prevention (CDC). Other quadrivalent flu shots are approved for people ages 3 and up.
So which one are you likely to get, and should you be opting for something different?
In general, you’re probably getting the quadrivalent vaccine, infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Lifestyle. “Most places are going to be primarily stocking the quadrivalent,” he says. “You want to get this vaccine because it covers against more strains.”
However, there is one big exception: The CDC recommends that people who are 65 and older get what’s called a high-dose influenza vaccine — which is another name for a trivalent vaccine. “Because of the way it’s formulated, it only has three strains,” Adalja says, explaining that with only three strains in the formula, you can make the doses a bit higher than with four. “It’s kind of a tradeoff: You’re getting the benefit of a higher dose against some of the more dangerous strains. In a high dose, there’s only so much you can pack into a vaccine.”
For the record, the CDC’s Advisory Committee on Immunization Practices does not state a preference for the quadrivalent or the trivalent. Still, the quadrivalent makes sense for many people, Adalja says. “The CDC doesn’t want to confuse people more,” he says. “They just want people to get something, which is much better than nothing.”
If you know you want to get your flu shot and aren’t sure which type you’re getting, just ask. Your doctor or pharmacist should be able to tell you.
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