From the Guidelines
Getting a flu shot during the off-season can still be beneficial in certain situations, particularly for travelers to the Southern Hemisphere or tropics and individuals at high risk of influenza complications. The best time to get vaccinated is before flu season begins, typically in the fall (September through October in the Northern Hemisphere) 1. However, if you missed this window, getting vaccinated later is still worthwhile as long as flu viruses are circulating, which can extend into spring.
Key Considerations
- The standard flu vaccine protects against four influenza viruses expected to be most common during the upcoming season.
- Protection develops about two weeks after vaccination and generally lasts through the flu season.
- For travelers going to the Southern Hemisphere or tropics during their flu seasons (which occur during the Northern Hemisphere's summer), off-season vaccination may be advisable.
- The vaccine's effectiveness can wane over time, so annual vaccination is recommended regardless of when you received your last dose 1.
High-Risk Groups
- Certain groups, such as pregnant women, children under 2 years, adults 65 years and older, and people with chronic medical conditions, are at higher risk of influenza complications and may benefit from off-season vaccination 1.
- Vaccination of close contacts of these high-risk individuals can also help reduce their risk of exposure to influenza.
Timing of Vaccination
- While there is concern about waning immunity from early vaccination, particularly in older adults, the current evidence suggests that vaccination should not be delayed to a later date, as this increases the likelihood of missing the influenza vaccination altogether 1.
- Annual vaccination is still the best way to protect against influenza, regardless of when you received your last dose.
From the Research
Flu Shot Off-Season Administration
- The provided studies do not directly address the advisability of giving flu shots off-season 2, 3, 4, 5, 6.
- However, the studies suggest that flu vaccination is most effective when administered at the beginning of flu season, which typically starts in October 2.
- It takes approximately 14 days after vaccination for a healthy adult to reach peak antibody protection 2.
- The influenza virus may undergo antigenic drift, making the vaccine less effective in some seasons 2.
- Vaccination is still recommended for all people 6 months of age or older, including pregnant and postpartum women, unless the individual has a contraindication 2.
- The studies emphasize the importance of vaccination in preventing influenza-related hospitalizations and reducing the burden on the healthcare system 5.
- Oseltamivir prescriptions filled on the day of diagnosis were associated with significantly decreased odds of hospitalization, highlighting the importance of timely treatment 5.
- Flu vaccination was associated with a lower odds for hospitalization, which is already well established 5.
Key Considerations
- The effectiveness of the flu vaccine can vary from season to season due to antigenic drift 2, 3, 4.
- Vaccination is still the primary preventive measure against influenza, and its importance cannot be overstated 2, 3, 4, 5, 6.
- The decision to administer a flu shot off-season should be made on a case-by-case basis, taking into account individual risk factors and medical history.