The Flu Shot for Children: What Parents Need to Know

Why children are a priority for flu vaccination

Influenza is not just a bad cold for young children. Children under five — and especially under two — have higher rates of flu-related hospitalization than school-age kids or most healthy adults, with an estimated 6,000 to 25,000 U.S. flu-related pediatric hospitalizations per season 1Ref 1Centers for Disease Control and Prevention (2024).Flu and Children.Annual recommendation for all children 6 months and older; 6,000–25,000 annual flu-related hospitalizations in children under 5; higher severity in children under 2; cocooning rationale. Young children's airways are smaller, their immune responses are less experienced, and respiratory complications are more serious at this age.

Certain children with underlying conditions — asthma, heart disease, diabetes, neurodevelopmental conditions — face even higher risk of severe flu illness and its complications, including pneumonia and encephalitis. The flu vaccine reduces the chance of infection, reduces severity if a vaccinated child still gets infected, and reduces household spread to infants and family members who cannot yet be vaccinated 1Ref 1Centers for Disease Control and Prevention (2024).Flu and Children.Annual recommendation for all children 6 months and older; 6,000–25,000 annual flu-related hospitalizations in children under 5; higher severity in children under 2; cocooning rationale. This last point matters: babies under six months are too young for the flu shot themselves and depend on the people around them being vaccinated — a strategy sometimes called 'cocooning.'

When to get vaccinated

Annual vaccination is recommended every flu season. The ACIP and AAP recommend vaccination ideally by the end of October to allow immune response to develop before flu activity peaks 2Ref 2Grohskopf LA, Blanton LH, Ferdinands JM, et al. (2024).Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the ACIP — United States, 2024–25 Influenza Season.Two-dose requirement for children aged 6 months–8 years in their first vaccination season (doses ≥4 weeks apart); timing recommendation (ideally by end of October); nasal spray contraindications including moderate-to-severe asthma3Ref 3American Academy of Pediatrics (HealthyChildren.org) (2026).Immunizations — Influenza (Flu) Vaccine.AAP annual flu vaccination recommendation for all children ≥6 months; timing by end of October; egg allergy no longer a contraindication. Getting vaccinated in November, December, or even later still provides benefit because flu season can extend into spring.

Very early vaccination (July or August) is generally not recommended because immunity may wane before the end of a long flu season, though the optimal timing can vary and the child's provider can advise.

The two-dose rule for first-timers under nine

For a child receiving a flu vaccine for the very first time — or who received only one dose in their first flu season — current guidelines recommend two doses spaced at least four weeks apart in the first season they are vaccinated 2Ref 2Grohskopf LA, Blanton LH, Ferdinands JM, et al. (2024).Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the ACIP — United States, 2024–25 Influenza Season.Two-dose requirement for children aged 6 months–8 years in their first vaccination season (doses ≥4 weeks apart); timing recommendation (ideally by end of October); nasal spray contraindications including moderate-to-severe asthma. The first dose primes the immune system; the second produces the full protective response.

After that first two-dose season, a single annual dose is all that is needed. Parents of young children who are new to the flu vaccine should plan for two visits, or ask whether the practice can time the second dose efficiently.

Shot vs. nasal spray — who can get which

The injectable flu vaccine (inactivated; contains no live virus) is approved from six months of age onward and is the form given to most young children.

The nasal spray flu vaccine (live-attenuated; weakened live virus) is approved for healthy children two years and older. It is not recommended for children with moderate to severe asthma, a history of wheezing in the past year (for children under five), certain immunocompromising conditions, or children currently on aspirin therapy 2Ref 2Grohskopf LA, Blanton LH, Ferdinands JM, et al. (2024).Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the ACIP — United States, 2024–25 Influenza Season.Two-dose requirement for children aged 6 months–8 years in their first vaccination season (doses ≥4 weeks apart); timing recommendation (ideally by end of October); nasal spray contraindications including moderate-to-severe asthma. It should also not be given to children who have received influenza antiviral drugs within the past 48 hours. Whether the nasal spray is appropriate depends on the child's health history — the provider at the visit makes that determination.

For children who are very anxious about needles, it may be worth asking whether the nasal spray is an option. Both forms are updated annually to match expected circulating strains; neither is inherently more effective than the other in most seasons, though in specific seasons when one form performs differently, the provider will have current guidance 2Ref 2Grohskopf LA, Blanton LH, Ferdinands JM, et al. (2024).Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the ACIP — United States, 2024–25 Influenza Season.Two-dose requirement for children aged 6 months–8 years in their first vaccination season (doses ≥4 weeks apart); timing recommendation (ideally by end of October); nasal spray contraindications including moderate-to-severe asthma.

What to expect afterward

After the injectable flu vaccine, mild soreness, redness, or a low-grade fever is common and typically resolves in one to two days 1Ref 1Centers for Disease Control and Prevention (2024).Flu and Children.Annual recommendation for all children 6 months and older; 6,000–25,000 annual flu-related hospitalizations in children under 5; higher severity in children under 2; cocooning rationale. After the nasal spray, some children have a brief runny nose for a few days. Neither form gives children the flu — the injectable vaccine contains no live virus and cannot cause influenza, and the nasal spray's weakened virus is not capable of causing influenza illness in healthy recipients.

Egg allergy, even severe allergy, is no longer a reason to avoid the flu vaccine or to require special precautions beyond the standard 15-minute post-vaccination observation — current guidelines from both the AAP and CDC reflect this 3Ref 3American Academy of Pediatrics (HealthyChildren.org) (2026).Immunizations — Influenza (Flu) Vaccine.AAP annual flu vaccination recommendation for all children ≥6 months; timing by end of October; egg allergy no longer a contraindication. Egg-free flu vaccine options (produced in cell culture or recombinant technology) are also available for families who prefer them. A child who has received the flu vaccine in prior years and has had no adverse reactions does not need pre-vaccination allergy testing regardless of egg allergy status. Signs of a serious allergic reaction — hives, swelling, breathing difficulty within minutes of the shot — are rare and should prompt immediate evaluation 1Ref 1Centers for Disease Control and Prevention (2024).Flu and Children.Annual recommendation for all children 6 months and older; 6,000–25,000 annual flu-related hospitalizations in children under 5; higher severity in children under 2; cocooning rationale.