Side Effects of Influenza Vaccine in the Elderly
The influenza vaccine is exceptionally safe in elderly adults, with local soreness at the injection site being the most common side effect, lasting up to 2 days and generally mild and not disabling. 1
Common Local Reactions
- Local soreness at the injection site is the most frequent side effect, typically lasting up to 2 days, and is generally mild and not disabling. 1
- High-dose vaccine recipients may experience more frequent injection site reactions compared to standard-dose recipients, though the safety profile remains favorable. 2
Systemic Symptoms
- Systemic symptoms including fever, malaise, and myalgias may begin 6-12 hours after vaccination and typically last 1-2 days. 1
- These systemic symptoms occur no more frequently than with placebo administration, meaning they are not truly caused by the vaccine at higher rates than expected by chance. 1
Critical Safety Context
- The vaccine cannot cause influenza infection because it does not contain live virus and the vaccine virus is completely inactivated. 1
- This is a crucial point to communicate to patients who may be hesitant due to misconceptions about "getting the flu from the flu shot."
Rare Adverse Events
- Rare immediate allergic reactions can occur in patients with egg hypersensitivity, as the vaccine is grown in eggs. 1
- Guillain-Barré syndrome was clearly associated only with the 1976 swine influenza vaccine and has not been associated with influenza vaccines since 1976. 1
Risk-Benefit Analysis
- The side effect profile is exceptionally favorable, especially when weighed against the substantial mortality reduction (45-68%) and hospitalization reduction (50%) that vaccination provides in elderly adults. 1
- The enhanced protection of high-dose vaccines outweighs the minimal increase in mild local reactions in adults ≥65 years. 2
High-Dose Vaccine Considerations
- While high-dose vaccines may produce slightly more local reactions, the 48% reduction in mortality risk and 27% reduction in hospitalization risk far outweigh these minor, self-limited side effects. 3
- The Advisory Committee on Immunization Practices (ACIP) recommends preferential use of higher-dose or adjuvanted influenza vaccines for all adults ≥65 years despite the slightly increased local reaction rates. 3, 2
Common Pitfall to Avoid
- Do not withhold vaccination due to concerns about side effects—the vaccine's safety profile is excellent, and over 80% of influenza-related deaths occur in elderly adults, making vaccination essential. 4
- Any influenza vaccine is superior to no vaccination, so if concerns about side effects arise, reassure patients that serious adverse events are extraordinarily rare and that mild local reactions resolve within 1-2 days. 2