What is the recommended influenza (flu) vaccine dose and schedule for an infant?

Influenza Vaccine Dosing Schedule for Infants

Infants should begin influenza vaccination at 6 months of age with either a 0.25 mL or 0.5 mL dose (depending on the specific vaccine product), and first-time recipients require 2 doses administered at least 4 weeks apart, ideally completed by the end of October. 1

Age Eligibility and Timing

• Influenza vaccination is recommended for all infants starting at 6 months of age and older 1, 2
• Vaccination is not licensed for infants younger than 6 months 3
• Household contacts and caregivers of infants under 6 months should be vaccinated to provide indirect protection through "cocooning" 4
• Vaccination should begin as soon as vaccine becomes available in early fall, with both doses ideally completed by the end of October for optimal protection before peak influenza season 1, 5

Dose Volume by Product (6-35 Months)

The specific dose volume varies by vaccine manufacturer: 1, 5

• Afluria (Seqirus): 0.25 mL per dose
• Fluzone (Sanofi Pasteur): Either 0.25 mL or 0.5 mL per dose (both demonstrated comparable safety and immunogenicity) 4
• Fluarix (GlaxoSmithKline): 0.5 mL per dose
• FluLaval (GlaxoSmithKline): 0.5 mL per dose
• Flucelvax (Seqirus): 0.5 mL per dose

Two-Dose Schedule for First-Time Recipients

Children 6 months through 8 years receiving influenza vaccine for the first time require 2 doses: 1

• Minimum interval between doses: at least 4 weeks apart 1, 2
• Doses given up to 4 days before the minimum interval are acceptable 1
• Children who received only 1 dose before July 1 of the current season also require 2 doses 1
• Children whose vaccination status is unknown should receive 2 doses 1

Single-Dose Schedule for Previously Vaccinated

Children who have received 2 or more total doses of influenza vaccine (at any time in their life, not necessarily in consecutive seasons) require only 1 dose in subsequent seasons 1, 2

Route of Administration

• Administer intramuscularly into the anterolateral thigh for infants 5, 3
• The vaccine should be clear and slightly opalescent; inspect for particulate matter before administration 3
• Shake the prefilled syringe or multi-dose vial before administering each dose 3

Vaccine Product Selection

• Any licensed, age-appropriate influenza vaccine can be used; no specific product is preferred over another 1
• The two doses in a season do not need to be the same brand 1
• Vaccination should not be delayed to obtain a specific product 1
• Only inactivated influenza vaccine (IIV) is appropriate for infants 6-23 months; live attenuated influenza vaccine (LAIV) is not licensed for children under 2 years 2, 6

Common Pitfalls to Avoid

• Delaying the second dose beyond the recommended interval leaves the infant inadequately protected during peak season 4
• Using incorrect dosage based on age and specific vaccine product 4
• Not completing the two-dose series for first-time recipients, which is essential for adequate immunity 4
• Splitting a 0.5 mL dose into two 0.25 mL doses is not acceptable 1
• Waiting for a specific vaccine brand when any age-appropriate product is available 1

Special Considerations for High-Risk Infants

• Infants with chronic medical conditions (cardiac disease, asthma, immunocompromise) should be prioritized for vaccination 1
• Reaction rates may be higher when administered with other routine vaccines, but this should not delay vaccination 4
• The most common adverse reactions in infants 6-35 months are pain/tenderness (>50%), redness (>25%), irritability and drowsiness (>25%) 1