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Why Didn’t FluMist Flu Vaccine Work? Your Questions Answered

News that vaccine advisers do not recommend FluMist, the only needle-free flu vaccine on the market, has parents despairing and has vaccine-haters saying ‘I told you so’.

But flu vaccines are different from all other vaccines, something the public tends to forget. Why are they so lousy and hard to make?

MedImmune's headquarters outside Washington DC, where FluMist was invented.

Here are some answers to your questions about flu vaccines.

Why didn’t it work?

Vaccine experts say they are not sure. The Advisory Committee on Immunization Practices, which advises the Centers for Disease Control and Prevention, cites one study that found FluMist only reduced the risk of serious influenza by 3 percent last year.

AstraZeneca, which owns FluMist’s Maryland-based maker MedImmune, disputes this and points to evidence from Britain showing it was more than 57 percent effective last flu season.

“We continue to believe FluMist Quadrivalent is an effective vaccine for the prevention of seasonal influenza as supported by the available evidence,” the company said in a statement.

Dread Needles? There Are Still Ways to Get the Flu Vaccine 0:42

Each flu vaccine is a cocktail, protecting against three or four strains. FluMist and other vaccines distributed in 2015-2016 protected against a particular strain of H1N1 flu, an H3N2 strain and one or two influenza B strains.

“The problem could be something specific related to the pandemic H1N1 virus,” said Dr. John Treanor, who tests flu vaccines at the University of Rochester Medical Center. “It might be something about the H1N1 live attenuated influenza vaccine (that’s FluMist) that makes it less effective or less stable, or it might have something to do with some unknown issue with protection against H1N1.”

Does this mean flu vaccines are a joke?

No, but it is true they’re less reliable than other vaccines. Influenza is very difficult to vaccinate against. The virus is so mutation-prone that the vaccine has to be changed and made fresh every year. Even so, sometimes the circulating strains mutate faster than the vaccine makers make new vaccine. And sometimes one strain circulates in the U.S. while others predominate in Europe or Asia.

So some years the vaccine is not very protective.

In past years, FluMist has been more effective than injected flu vaccines, probably because it is a “live” virus, meaning it’s a whole influenza virus that has been weakened. Vaccination causes an extremely mild infection that, in theory, protects as well as actually having flu.

Flu’s constant mutation explains why having it once doesn’t make people immune in the same way that having measles or mumps does.

Why can’t we have a better flu vaccine?

Scientists are working hard on it. They’re looking for a “universal” flu antigen – a piece of the virus that is the same from one strain to another and that doesn’t mutate.

Because vaccines in general are not a big profit-maker for drug companies, there’s not a lot of incentive to pour big research dollars into making a better flu vaccine, so the work’s left to small biotech companies, academic research labs and the federal government. The work competes for funding against diseases from Alzheimer’s to Zika in a world of limited taxpayer and investor cash.

Is it better to just get flu naturally?

No, because flu can kill. And see above: Having flu once doesn’t protect you from getting a different strain, or just a lightly mutated version of a strain you’ve had before. And sometimes people die quickly and without warning, and sometimes previously perfectly healthy people die from flu. Flu kills anywhere between 4,000 and 50,000 people a year in the United States.

The CDC says people who get vaccinated may still get influenza, but they are much less likely to get a serious infection that puts them into the hospital or kills them.

And people who think they can “boost” their immune systems by eating garlic or taking supplements are pretty much fooling themselves. While poor eating or a lack of exercise or sleep can make people more vulnerable to infection, there’s no proven way to supercharge the immune system to ward off infectious diseases.

Will there be a shortage of flu vaccines this fall?

Probably not. FluMist made up about 8 percent of the U.S. flu vaccine supply last year, even though it’s given to about a third of children who get vaccinated every year.

The CDC says almost everyone over the age of 6 months should get a flu vaccine every year, but usually only about half of those people ever do, meaning flu vaccines get thrown out every year. While may pediatricians may have already put in their orders for FluMist this year, there’s still time for them to change their orders before deliver starts in August or September.