Skip to content

    Vaccines Health Center

    Font Size

    Flu Vaccine FAQ

    What the CDC Wants You to Know About the 2010-2011 Flu Vaccine

    I hear the H1N1 swine flu vaccine is included in the seasonal vaccine. Doesn't that make the seasonal vaccine much less safe? continued...

    Our monitoring showed the side effects of the H1N1 vaccine were pretty much the same as you'd see from regular seasonal vaccines. There was no indication the pandemic vaccine was any less safe than any vaccine we've ever produced.

    So including that vaccine as one of the three in this year's seasonal vaccine will not change the safety pattern. Even so, we will monitor the safety of this year's seasonal vaccine closely-- as we always do.

    My children are under 9 years old. How many doses of the seasonal flu vaccine do they need?

    It's really quite complicated for parents whose children are 8 years old or younger and who have never been fully vaccinated against the flu.

    How many doses of flu vaccine will a child under age 9 years need this year? It will depend on two things:

    • Whether the child got any H1N1 vaccine AND
    • Whether the child previously got a seasonal vaccination, when that was given, and how many doses they got.

    Children who got a previous seasonal flu vaccine as recommended -- AND got just one dose of the H1N1 pandemic vaccine last year -- need only one dose of the seasonal vaccine this year. We give them credit for getting the priming dose last year, but only if they previously got the seasonal vaccine.

    Children under age 9 years who never before got a seasonal flu vaccination will need two doses of the seasonal vaccine this year -- even if they got the 2009 H1N1 pandemic flu vaccine.

    Children under age 9 years who have had a previous flu vaccination but who did not get the 2009 H1N1 pandemic flu vaccine will need two doses of the seasonal vaccine this year.

    If a child needs two doses of the flu vaccine, the second dose must be given no sooner than four weeks after the first dose.

    It's such a hassle to get young children two doses of flu vaccine a month apart. Won't they get at least some protection from a single dose of the vaccine?


    This year, the number of doses is driven by the pandemic virus component of the vaccine. Studies at the National Institutes of Health show that children do not respond well to a single dose of the 2009 H1N1 vaccine. A single dose does not provide protection to a very large number of young children.

    We are not just making this up. The data show two doses are absolutely necessary. Yes, it can be a hassle to take them back a month later for their second dose -- but it greatly improves the chances the child will be protected.

    Today on WebMD

    passport, pills and vaccine
    25 ways to protect yourself from illness.
    syringes and graph illustration
    Create a personalized schedule.
    flu shot signage
    Get answers to your questions
    gloved hand holding syringe
    Which ones do you need?
    woman walking
    Vaccine Schedule Are Your Childs Shots Up To Date
    69x75 thumbnail early pregnancy 02
    gloved hand holding syringe
    adult vaccine injection
    woman peeking under sheets
    cold season and vitamin C
    Adult Meningitis Vaccines What You Should Know