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Why bother getting the flu shot? What you need to know about mutated virus

One strain of flu virus has mutated this year and the vaccine may not protect against it, the Centers for Disease Control and Prevention reports. The flu season's barely started this year, but most people haven't been vaccinated yet and may be wondering whether it's still worth it.Here's what you need to know: Should we still get the vaccine?CDC says yes. The vaccine protects against three or fou

One strain of flu virus has mutated this year and the vaccine may not protect against it, the Centers for Disease Control and Prevention reports. The flu season's barely started this year, but most people haven't been vaccinated yet and may be wondering whether it's still worth it.

Here's what you need to know: 

Should we still get the vaccine?

CDC says yes. The vaccine protects against three or four different strains of influenza — not just the H3N2 strain, which is the one that has mutated or “drifted," but also either one or two B strains, depending on the vaccine, and the H1N1 strain. 

Only about half the H3N2 strains out there have mutated. The other half match the vaccine. And it’s possible the vaccine might provide cross-protection, meaning that even if you got infected with the mutant H3N2, you’d still be less likely to get really sick.

Is it too late to make a new version of the vaccine?

Yes, because it takes months to make flu vaccines. Influenza vaccines are based on really old technology that relies first on getting samples of virus from real patients and then growing them in chicken eggs. This process takes about six months, so the CDC chooses which strains will go into the flu vaccine in February for vaccines that will be distributed starting in August.

There are some faster technologies, but even the fastest one takes four months. Some of the newer vaccines are grown in cell cultures instead of eggs, and one, called Flublok, is made just using DNA. 

What scientists are working for is a “universal” flu vaccine that could protect people against all strains of influenza, or at least one that could be made more quickly.

Flu season in the U.S. usually peaks during January and February, so it's not too late to get your shot. And, yes, you still should get vaccinated.Justin Sullivan / Today

What happened with the nasal spray version of the vaccine?

The nasal spray vaccine, called FluMist, is a needle-free version that’s sprayed up the nose. It’s made the old-fashioned way, using eggs, and is general considered more effective because it uses a live but weakened flu virus. 

But last year, for some reason it didn’t match the H1N1 strain that was circulating. This year, it appears to, and CDC says because it’s a “live” vaccine it may protect against the drifted H3N2 better than other vaccines.

Is the virus season looking bad so far or average?

It’s still early so it’s hard to tell, but CDC is worried that it could be a bad year because the H3N2 is dominating. 

“We know that in seasons when H3 viruses dominate, we tend to have worse seasons for flu,” CDC director Dr. Tom Frieden told reporters. So far this year, five children have been reported to have been killed by influenza. 

Flu season usually peaks in the U.S. in January and February.

How often do they get the flu vaccine component wrong?

As Frieden likes to say, “every season is different.” 

Because the flu vaccine is formulated so far in advance of the annual flu season, it can often be off. One thing flu viruses do really well is mutate, and they are unpredictable. They can mutate mid-season, or a whole new virus can pop up, like in 2009, when the H1N1 swine flu appeared suddenly in March and April, at what should have been the end of flu season.

What else can you do besides get vaccinated?

CDC is reminding people that there are two drugs that can help flu: Tamiflu and Relenza. 

Anyone at high risk of complications — if you have asthma or diabetes, or heart disease and even people who are obese — it’s important to see a doctor right away if you get symptoms of flu. People in nursing homes can take these drugs to protect against flu. And, as always, frequent handwashing can really help protect against flu, as people can pick up the virus on their fingers and carry it to the nose, mouth and eyes.

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