When is the best time to get an influenza (flu) vaccination?

Best Time to Get a Flu Shot

The optimal time to get a flu shot is during October and November, with vaccination efforts focused on high-risk individuals in October and the general population in November. 1

Timing Recommendations by Priority Group

High-Priority Groups (October Focus)

• Persons aged >50 years
• Persons with high-risk medical conditions (any age)
• Children aged 6-23 months
• Healthcare workers
• Household contacts of high-risk individuals
• Children <9 years receiving vaccine for the first time (need booster dose)

General Population (November Focus)

• Healthy adults under 50 years
• Anyone else wishing to reduce their risk of influenza

Benefits of October-November Timing

This timing recommendation balances several important factors:

1. Peak Antibody Protection: Adults develop peak antibody protection approximately 2 weeks after vaccination 2

2. Seasonal Influenza Patterns: In the United States, influenza activity typically begins to increase in October/November but doesn't reach peak levels until late December through early March 1

3. Duration of Protection: Antibody levels can begin to decline within months after vaccination, particularly in older adults 1

4. Vaccine Waning: Recent research suggests intraseason waning of vaccine effectiveness, with protection decreasing by approximately 16% for each additional 28 days since vaccination 3

Special Timing Considerations

Early Vaccination (September)

• For high-risk individuals: Can be offered during routine healthcare visits to avoid missed opportunities 1
• Not recommended for nursing home residents: Antibody levels may decline too quickly before peak flu season 1

Late Vaccination (December and Beyond)

• Should continue to be offered throughout the influenza season as long as vaccine supplies are available
• Still beneficial even after influenza activity has been documented in the community 1
• Better late than never approach is supported by evidence

Dosing Considerations

• Children <9 years receiving flu vaccine for the first time: Need two doses administered at least 1 month apart

  • First dose should be given in October (or earlier if possible)
  • Second dose ideally before December 1

• Adults and previously vaccinated children: Only one dose needed

Emerging Research on Timing

Recent studies suggest potential benefits to slightly delayed vaccination, particularly for older adults:

• Research from 2018 found that modest delays in immunization could prevent 0.44-11.97% of the current disease burden, depending on the season and waning rate 4

• A 2024 study suggests that in scenarios with fast waning immunity, all age groups might benefit from delaying vaccination, while with slower waning, the optimal timing varies based on initial vaccine effectiveness and peak timing of the flu season 5

Common Pitfalls to Avoid

1. Waiting too long: Delaying vaccination until December or later risks exposure during early seasonal outbreaks

2. Getting vaccinated too early: Vaccination before September (especially for older adults) may result in waning immunity before peak flu season

3. Missing the second dose for children: Failing to complete the two-dose series for children <9 years receiving the vaccine for the first time

4. Skipping vaccination due to late timing: Believing it's "too late" to get vaccinated after December - vaccination is beneficial throughout the entire flu season

Bottom Line

For maximum protection against influenza morbidity and mortality, get your flu shot in October if you're in a high-risk group, or in November if you're part of the general population. If you miss these optimal windows, vaccination at any point during flu season is still beneficial and recommended.