As people age, their immune system naturally weakens, a process known as immunosenescence. This makes adults 65 and older more vulnerable to the flu and its serious complications, including pneumonia, hospitalization, and death. Standard-dose flu vaccines may not provide as robust an immune response in this age group as they do in younger adults. In response, public health bodies like the Centers for Disease Control and Prevention (CDC) have developed and preferentially recommend more potent vaccines specifically for seniors.
Why older adults need a more potent flu vaccine
Older adults face a disproportionately high burden of severe flu-related illness. Data from past flu seasons indicate that seniors account for a significant majority of hospitalizations and deaths related to the flu. The effectiveness of the standard-dose vaccine can be lower in this population due to the age-related decline in immune function. The specialized, higher-potency vaccines are engineered to counteract this effect by stimulating a stronger immune response, thereby providing better protection.
The three recommended vaccine options for seniors
The CDC preferentially recommends three types of injectable flu vaccines for adults 65 and older, citing studies that suggest these options are potentially more effective than standard-dose formulations. These options are all quadrivalent, meaning they protect against four different flu virus strains: two influenza A viruses and two influenza B viruses.
- High-Dose Inactivated Flu Vaccine (Fluzone High-Dose Quadrivalent): This vaccine contains four times the amount of antigen as a standard flu shot. This higher concentration is designed to produce a more potent immune reaction and higher levels of protective antibodies in older adults.
- Adjuvanted Inactivated Flu Vaccine (Fluad Quadrivalent): This vaccine contains the same amount of antigen as a standard-dose shot but includes an adjuvant—a substance that helps create a stronger, more lasting immune response. The adjuvant essentially boosts the body's reaction to the vaccine.
- Recombinant Flu Vaccine (Flublok Quadrivalent): This egg-free vaccine is created using recombinant DNA technology, which results in a vaccine with three times the amount of antigen as a standard dose. It is also recommended for adults aged 18 and older, including those with severe egg allergies.
If none of these three preferentially recommended vaccines are available, older adults should still receive any other age-appropriate flu vaccine. Any vaccine is better than none.
Comparing senior flu vaccine options
| Feature | High-Dose Flu Vaccine (e.g., Fluzone HD) | Adjuvanted Flu Vaccine (e.g., Fluad) | Recombinant Flu Vaccine (e.g., Flublok) |
|---|---|---|---|
| Mechanism | Contains four times the amount of antigen compared to standard shots. | Contains an adjuvant to boost the immune response to the standard antigen amount. | Contains three times the antigen, produced without eggs using recombinant technology. |
| Effectiveness (vs. standard dose) | Evidence shows a stronger immune response and better protection in those 65+. Some studies report significantly reduced hospitalization risks. | Data suggests improved effectiveness against flu, pneumonia, and related hospitalizations. | Studies indicate a better response in older adults than standard vaccines. Egg-free composition is a key feature. |
| Ingredients | Egg-based. | Egg-based; contains the MF59 adjuvant. | Egg-free. |
| Target Population | Licensed and approved for people aged 65 and older. | Licensed and approved for people aged 65 and older. | Licensed for people aged 18 and older, including seniors. |
| Side Effects | Typically mild and similar to standard shots, but may occur more frequently (e.g., pain, tiredness, headache). | Mild and similar to other vaccines, but potentially more common than standard dose due to the adjuvant. | Mild and similar to other inactivated vaccines. |
Frequently asked questions about flu vaccines for seniors
Can people under 65 get the senior flu shot?
High-dose and adjuvanted vaccines are approved for individuals aged 65 and older. While off-label use in certain immunocompromised adults under 65 may occur, it requires a doctor's discussion.
How soon does the flu vaccine start to work?
Protection usually develops about two weeks after vaccination. Early fall vaccination is important for protection before flu activity increases.
What are the side effects of the senior flu shots?
Side effects are typically mild and short-lived (1-3 days), including injection site soreness, headache, muscle aches, or fatigue. Serious side effects are rare.
Is it safe to get the senior flu shot with other vaccines?
Yes, flu vaccines can be administered concurrently with other vaccines like COVID-19 or pneumococcal shots. Staying current on all recommended immunizations is advised.
What if a preferred vaccine option is not available at my clinic?
If preferred high-dose, adjuvanted, or recombinant vaccines are unavailable, the CDC advises getting a standard-dose vaccine. Receiving any flu vaccine offers protection and is better than none.
When is the best time for seniors to get their flu shot?
September or October is generally the best time for adults 65 and older to get vaccinated. Early vaccination in summer might lead to waning immunity later in the season.
Can a person with an egg allergy get the senior flu shots?
Most individuals with egg allergies can receive egg-based flu vaccines like Fluzone High-Dose or Fluad. The egg-free recombinant Flublok is also an option for seniors, particularly those with severe egg allergies. Discuss the best choice with your doctor.
Conclusion
For adults aged 65 and older, the decision to get a flu vaccine comes with specific considerations. Due to a less robust immune response with age, the Centers for Disease Control and Prevention (CDC) preferentially recommends enhanced flu vaccines—high-dose, adjuvanted, or recombinant—which are specifically formulated to provide better protection against the flu and its severe complications. These options provide a stronger immune boost than standard-dose versions. If these preferred options are not accessible, getting any age-appropriate flu vaccine is still highly beneficial. Discussing vaccine options with a healthcare provider is the best way to ensure maximum protection during flu season.
