Seasonal Influenza Vaccine Dosage & Administration

Questions & Answers

Can I pre-fill syringes for a flu shot clinic? If so, how long before the clinic can I pre-fill the syringes?

CDC does not recommend pre-filling syringes because of the potential for administration errors. The same person who draws vaccine should ideally be the person who administers it. Once the needle is placed on the syringe it should be used immediately. Any syringes except those filled by the manufacturer should be discarded at the end of the clinic day.

What is the appropriate dosing of a child less than nine years of age being vaccinated for the first time?

Children less than nine years of age being vaccinated for the first time should receive two doses of influenza vaccine, spaced at least 4 weeks apart in the initial year. For inactivated (injectable) vaccine, the dose for children aged 6-35 months is 0.25cc, and the dose for children aged 36 months-9 years is 0.5cc. For live attenuated vaccine (intranasal), the dose for children of all ages (and adults) is a 0.2 cc sprayer.

How many doses should be given to a child less than nine years of age in the second season of vaccination, if the child only received a single vaccine dose during the first season of vaccination?

This child should receive two doses of vaccine, spaced at least 4 weeks apart during the second season of vaccination. For a child beyond the second season of vaccination, however, only a single dose of vaccine is recommended, even if the child only received one dose in each of the first two years of being vaccinated.

FOR EXAMPLE: a child who got one dose at age two years of age, skipped a year, then presents at age four years of age only gets one dose that year.

What length of needle should we use to give influenza vaccinations to adults?

A 1- to 1.5-inch needle should be used to give inactivated influenza vaccine intramuscularly to adults.

Does protection from seasonal influenza vaccine decline or wane within 3 or 4 months of vaccination? Should I wait until October or November to vaccinate my elderly or medically frail patients?

CDC recommends that seasonal influenza vaccine be administered to all age groups as soon as it becomes available. Antibody to seasonal inactivated influenza vaccine declines in the months following vaccination. However, antibody level at a point several months after vaccination does not necessarily correlate with clinical vaccine effectiveness. There are no studies that compare vaccine effectiveness according to the month when the vaccination was given. The authors of a recent review on antibody declines among the elderly after vaccination reported that "In conclusion, we found no compelling evidence for more rapid decline of the influenza vaccine–induced antibody response in the elderly, compared with young adults, or evidence that seroprotection is lost at 4 months if it has been initially achieved after immunization." (see Skowronski et al, Rapid Decline of Influenza Vaccine–Induced Antibody in the Elderly: Is It Real, or Is It Relevant? Journal of Infectious Diseases 2008;197:490-502). In addition, there is a lack of evidence for late season outbreaks among vaccinated persons that can be attributed to waning immunity.

If adult inactivated influenza vaccine is not available, can a high-risk adult or a high-risk child receive the pediatric product (thimerosal preservative-free 0.25 ml dose) as long as they are given 0.5ml?

If there is not an adequate supply of adult formulation, providers vaccinating high-risk individuals requiring 0.5mL of influenza vaccine when the provider has only the 0.25mL prefilled syringes of pediatric vaccine may choose to give two separate injections of the 0.25mL product to protect the high-risk individual. Providers should never attempt to transfer vaccine from one syringe to another for the purpose of administering only one injection.

Currently, there is ample supply for this season. If an adequate supply of adult formulation is available in the community, CDC does not recommend that providers combine two 0.25mL doses of pediatric influenza vaccine to vaccinate a single individual who requires a 0.5mL dose of vaccine.

A child age 3 to 9 years being vaccinated for the first time mistakenly receives a 0.25mL (pediatric) dose rather than the recommended 0.5mL dose. Should the first dose be repeated?

Any vaccination using less than the standard dose should not be counted, and the person should be re-vaccinated according to age. The second dose should be administered at least 4 weeks after the first dose and should be 0.5mL.

Should I repeat a dose of influenza vaccine administered by an incorrect route (such as intradermal or subcutaneous)?

If the DOSE (amount) of vaccine was age-appropriate, it can be counted as valid regardless of the ROUTE by which it was given.

Should I repeat a dose of influenza vaccine that is less than the recommended dose (0.25mL for children 6-35 months; 0.5mL for persons 36 months and older)?

If less than an age-appropriate dose of influenza vaccine is administered it should NOT be counted as valid regardless of the route it was given, and should be repeated.