Influenza vaccination is suggested for preventing influenza in adults of 65 years or older.
The recommendation attaches a relatively high value on the possibility of avoiding severe influenza and influenza-like-illness (ILI) and on reducing transmission to vulnerable people (e.g. spouses or other inhabitants of nursing homes). Cost per QALY of influenza vaccinations in the elderly is acceptable 2.
A Cochrane review [Abstract] 1 included 8 studies with over 5000 persons of 65 years or older. Older adults receiving the influenza vaccine may experience less influenza over a single season compared with placebo, from 6% to 2.4% (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.27 to 0.66). Older adults probably experience less influenza-like illness (ILI) compared with those who do not receive a vaccination over the course of a single influenza season (3.5% versus 6%; RR 0.59, 95% CI 0.47 to 0.73). These results indicate that 30 people would need to be vaccinated to prevent one person experiencing influenza, and 42 would need to be vaccinated to prevent one person having an ILI. T1
An observational study with regression discontinuity design 3 followed the sharp change in vaccination rate at age 65 years that resulted from an age-based vaccination policy in the United Kingdom. Comparisons were limited to individuals who were 55 to 75 years old and were thus plausibly similar along most dimensions except vaccination rate. The data included 170 million episodes of care and 7.6 million deaths. Turning 65 was associated with a statistically and clinically significant increase in rate of seasonal influenza vaccination. No evidence indicated that vaccination reduced hospitalizations or mortality among elderly persons.
A cohort study using the United Kingdom general practice research database 4 compared rates of admissions for acute respiratory diseases and rates of death due to respiratory disease in individuals >64 years of age over 692,819 person-years in vaccine recipients and 1,534,280 person-years in vaccine nonrecipients. The pooled effectiveness of vaccine against hospitalizations for acute respiratory disease was 21% (95% confidence interval [CI], 17%-26%). Among vaccine recipients, no important reduction in the number of admissions to the hospital was seen outside influenza seasons. The pooled effectiveness of vaccine against deaths due to respiratory disease was 12% (95% CI, 8%-16%). Clear protection against death due to all causes was not seen.
A review of the effectiveness of influenza vaccine in aging and older adults 5 analyzed literature including meta-analyses and observational clinical studies. The vaccine effectiveness data showed a consistently lower response among older adults (≥65 years) than among people aged 15-64 years. Among the elderly, vaccination was most effective for individuals living in institutional settings, and the usefulness of vaccines in the community was modest.
Comment: The quality of evidence is downgraded by study limitations (biases in the design or conduct of the studies, lack of detail regarding the methods used to confirm the diagnosis of influenza) .
| Diagnosis | Anticipated absolute effects* (95% CI) | Relative effect(95% CI) | №of participants(studies) | Quality of the evidence(GRADE) | |
| Risk with placebo | Risk with influenza vaccine | ||||
| Influenza confirmed serologically | 57 per 1000 | 24 per 1000(15 to 38) | RR 0.42(0.27 to 0.66) | 2217(3 RCTs) | C |
| ILI by clinical assessment | 59 per 1000 | 35 per 1000(28 to 43) | RR 0.59(0.47 to 0.73) | 6894(4 RCTs) | B |
The following decision support rules contain links to this evidence summary:
Primary/Secondary Keywords