Sunday, November 9, 2014

What if the flu vaccine doesn't cover the right strains?

Recent news reported that the FluMist nasal spray might not cover the Influenza A H1N1 strain as well as the injectable might. I know this may cause concern for parents whose children have already gotten the FluMist vaccine this season.

Don't panic! (Gee, I've said that a lot this year with the delayed shipments of flu vaccine...)

Why not panic? 

First, this is a theoretical concern. It is based on the findings that the FluMist didn't cover the H1N1 well last season and it is the same vaccine this year.

Second, the main strains of influenza that are starting to circulate this year are NOT that H1N1 strain anyway.

I thought FluMist was preferred this year...

The CDC continues to state that the preferred vaccine for 2-8 year olds is the FluMist because it seems to be more effective than the injectable form against the other strains contained in the vaccines. (This is of course only if the child doesn't have contraindications to the FluMist and the FluMist is available. No one should delay vaccination if one form is available to wait for another form.)

Should we wait to get the shot? I know there are shipping delays...

Both the CDC and the AAP state to give whatever vaccine is available as appropriate and to not delay giving the vaccine to wait for another type. This makes sense. If you can be vaccinated with only one type due to the shipping delays, why risk being completely unprotected when you can get a vaccine that will most likely protect. No vaccine is 100% effective. With influenza we have the additional difficulty that the flu virus changes each year, but there is some protection across types when the flu vaccine is given.

Why doesn't the strain match?

Flu strains change every year and scientists predict what strains will be circulating. The vaccine companies all make vaccine against the predicted strains. This year the main strains that have been identified in people sick with the flu are Influenza A H3N2 and Influenza B. It is still early in the season, so findings might change, but so far both the FluMist and injectable vaccines seem to be effective against those strains. The FluMist appears to offer better protection than the injectable if the strains are not quite matched.

In short: 

Any age-appropriate influenza vaccine should be used as soon as possible to protect as many people as possible against the flu.

Do kids who got the FluMist need to be given a shot this year?

No. It is not recommended to do a second vaccination unless it is the first flu vaccine and a child needs a booster dose this season. It is appropriate to use either form of the vaccine for eligible children over 2 years, and mixing and matching is okay, but there is no recommendation specifically to do that.

The good news: 

We are starting to see shipments of flu vaccine! Hopefully we'll soon be able to vaccinate your children!

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