Who should get the influenza vaccination and how often?

Who Should Get the Influenza Vaccination and How Often

All persons aged 6 months and older should receive annual influenza vaccination, with no exceptions unless specific contraindications exist. 1

Universal Annual Vaccination Recommendation

The Advisory Committee on Immunization Practices (ACIP) and the American Academy of Pediatrics recommend annual influenza vaccination for everyone 6 months of age and older, regardless of risk status. 1, 2 This represents a shift from earlier risk-based approaches to universal vaccination, recognizing that influenza causes substantial morbidity across all age groups. 1

Priority Populations Requiring Emphasis

While vaccination is universal, certain groups warrant particular focus due to higher risk of severe complications and death:

High-Risk Medical Groups

• All children aged 6 through 59 months (under 5 years), who experience hospitalization rates comparable to elderly populations 1, 3
• All persons aged 50 years and older 1
• Persons with chronic conditions including pulmonary disease (including asthma), cardiovascular disease (excluding isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes) 1
• Immunocompromised persons from any cause, including medication-induced immunosuppression or HIV infection 1
• Pregnant women at any time during pregnancy 1, 2
• Residents of nursing homes and long-term care facilities 1
• Persons with extreme obesity (BMI ≥40 for adults) 1
• American Indian or Alaska Native persons 1

Transmission Prevention Groups

• All healthcare personnel, including paid and unpaid workers in healthcare settings with potential exposure to patients or infectious materials 1
• Household contacts and caregivers of children under 5 years, especially those under 6 months who cannot yet be vaccinated 1, 4
• Household contacts and caregivers of persons with high-risk medical conditions 1

Vaccination Frequency: Annual Administration

Influenza vaccination must be administered every year for several critical reasons:

• Antigenic drift causes circulating influenza strains to change annually, requiring updated vaccine formulations 1
• Waning immunity occurs over months, with antibody levels declining substantially within a single year 5
• Annual vaccination is required even when vaccine strains remain unchanged from the previous season due to immunity decline 4

Age-Specific Dosing Schedules

Children 6 Months Through 8 Years

Two-dose requirement for inadequately vaccinated children:

• Children who have received fewer than 2 total doses of influenza vaccine before July 1 of the current season require 2 doses administered at least 4 weeks apart 1, 4, 6
• Children who have previously received 2 or more total doses require only 1 dose annually 6
• Both doses should ideally be completed by the end of October to ensure protection before peak season 4

Children 9 Years and Older, Adolescents, and Adults

• One dose annually, regardless of prior vaccination history 6
• Even first-time recipients aged 9 years and older need only a single dose 6

Optimal Timing

• Begin vaccination as soon as vaccine becomes available, typically in early fall 4
• Ideally complete by end of October, as peak influenza season typically occurs in January or later in 75% of seasons 7
• Continue vaccination throughout the season as long as viruses are circulating and unexpired vaccine is available 7

Vaccine Selection

Inactivated Influenza Vaccine (IIV)

• Suitable for all persons 6 months and older 1
• Administered intramuscularly 4
• Preferred for immunocompromised persons, pregnant women, and those with contraindications to LAIV 1

Live Attenuated Influenza Vaccine (LAIV)

• Approved for healthy persons aged 2-49 years 1, 5
• Administered intranasally 5
• Preferred for children 2 years and older when not contraindicated 2
• Not recommended for children under 2 years, those with recurrent wheezing, immunocompromised persons, pregnant women, or contacts of severely immunocompromised persons requiring protected environments 1, 5

Common Pitfalls to Avoid

• Do not delay vaccination to obtain a specific product—any available age-appropriate vaccine should be administered immediately 6
• Do not skip the second dose in children under 9 years receiving their first vaccination series, as this leaves them inadequately protected 4
• Do not defer vaccination for minor illnesses with low-grade fever or mild upper respiratory symptoms—these are not contraindications 7
• Do not forget household contacts of infants under 6 months, who cannot themselves be vaccinated and depend on cocooning for protection 4, 8
• Do not confuse age-based requirements with first-time vaccination status—children 9 years and older need only one dose even if never previously vaccinated 6