What are the Canadian recommendations for the first flu shot in a healthy 6-month-old infant?

Canadian Recommendations for First Flu Shot in a 6-Month-Old Infant

A healthy 6-month-old infant in Canada should receive two doses of inactivated influenza vaccine (IIV), with the first dose administered as soon as vaccine becomes available (ideally by end of October), followed by a second dose at least 4 weeks later. 1, 2

Dosing Schedule for First-Time Recipients

Two-dose requirement is mandatory for vaccine-naive infants:

• Children 6 months through 8 years receiving influenza vaccine for the first time require 2 doses administered at least 4 weeks apart 3, 1, 2
• Both doses should ideally be completed before the end of October to ensure protection before influenza activity peaks 1
• The second dose is critical—only completing one dose leaves the child inadequately protected during peak influenza season 1

Dose Volume Options

For infants 6-35 months of age, dose volume depends on the specific vaccine product:

• Fluzone Quadrivalent: Either 0.25 mL or 0.5 mL per dose (both volumes demonstrated comparable safety and immunogenicity) 3, 1, 4
• FluLaval Quadrivalent: 0.5 mL per dose (15 μg hemagglutinin per virus strain) 3, 2
• Fluarix Quadrivalent: 0.5 mL per dose 3, 2
• Afluria Quadrivalent: 0.25 mL per dose 1, 2

The key is to use the appropriate volume for the specific product being administered—care must be taken to avoid dosing errors as formulations differ between manufacturers 3

Administration Details

Route and site of injection:

• Administer intramuscularly into the anterolateral thigh of infants 3, 1
• Vaccine should be stored at 2°C to 8°C (35°F–46°F) 3
• Shake the prefilled syringe or vial before administering each dose 4

Timing Considerations

Optimal vaccination timeline:

• Begin vaccination as soon as vaccine becomes available in the fall 3, 1
• Complete both doses before the end of October when possible 1, 2
• However, vaccination should continue throughout the influenza season as long as viruses are circulating and unexpired vaccine is available 3, 2
• Influenza activity can occur as early as October or extend through May, making timely vaccination critical 3

Concurrent Vaccination

Can be given with other routine vaccines:

• Influenza vaccine can be administered at the same visit with all other recommended routine vaccines 3
• Reaction rates may be higher when administered with other vaccines (particularly pneumococcal conjugate vaccine), but this should not delay vaccination 3, 1
• The benefits of timely, simultaneous vaccination outweigh the small risk of febrile seizures 3

Safety Profile

Expected adverse reactions in this age group:

• Most common injection-site reactions: pain/tenderness (>50%), redness (>25%) 4
• Most common systemic reactions: irritability and drowsiness (>25% of infants 6-35 months) 4
• Reactions are generally mild and resolve within 3 days 5
• Fever >38°C occurs in approximately 5.4% of vaccinated infants 6

Priority Populations

All healthy 6-month-olds should be vaccinated, but special emphasis for:

• Infants with chronic medical conditions (asthma, cardiac disease, immunosuppression, etc.) 3
• Infants 6-23 months are at substantially increased risk for influenza-related hospitalizations 2
• Up to 80% of influenza-associated pediatric deaths occur in unvaccinated children 6 months and older 7

Common Pitfalls to Avoid

Critical errors to prevent:

• Delaying the second dose beyond 4 weeks minimum interval—this leaves the child inadequately protected during peak season 1
• Using incorrect dose volume for the specific vaccine product—different manufacturers require different volumes (0.25 mL vs 0.5 mL) 3, 1
• Waiting to obtain a specific vaccine product—vaccination should not be delayed; use any available, age-appropriate product 3
• Assuming one dose is sufficient—vaccine-naive children under 9 years absolutely require two doses for adequate immunity 3, 1
• Deferring vaccination for minor illnesses—mild upper respiratory symptoms, low-grade fever, or allergic rhinitis are NOT contraindications 7

Contraindications

Do not administer if:

• History of severe allergic reaction (anaphylaxis) to any vaccine component, including egg protein, or to a previous dose of any influenza vaccine 4
• Moderate to severe acute illness with high fever—defer until clinical recovery 7, 4

Protection of Household Contacts

Cocooning strategy for additional protection:

• All household contacts and caregivers should receive influenza vaccination to provide indirect protection to the infant 3, 1
• Pregnant women can safely receive influenza vaccine at any point during pregnancy, which also provides protection to infants during their first 6 months through transplacental antibody transfer 3