Influenza is a serious health concern among elderly people. Each year in Canada, up to 75,000 people are admitted to hospital with influenza, and of these, the number of deaths has ranged from 1,500 to 6,700.1,2 In particular, people over the age of 65 are at risk of developing complications of infection. It has been estimated that 90% of influenza-related deaths in Canada are of people in this age group, and half of these occur in long-term care facilities.3,4 Institutionalized elderly are especially vulnerable because of their advanced age and underlying illnesses (high-risk conditions include chronic respiratory or cardiac disease, renal disease, diabetes and cancer), as well as their close mutual proximity with a range of caregivers. Of the three types of influenza virus (A, B, C), influenza A is responsible for the more severe illness and can lead to pneumonia, hospitalization and even death in the elderly and those with chronic illnesses.
The Canadian National Advisory Committee on Immunization (NACI) recommends annual influenza vaccination for all people over the age of 65 years,5 as well as for health care workers and personnel who have significant contact with people in high-risk groups. Immunization is more effective if given at least two weeks before the beginning of the active flu season (by mid-November), although the elderly should be advised to receive their vaccination earlier in October.
The effectiveness of influenza vaccine depends upon the age and immunocompetence of the recipient and how closely the vaccine matches the virus strain. With a good match, vaccination has been shown to prevent influenza in 70-90% of healthy adults and children, and is approximately 70% effective in preventing hospitalization for pneumonia and influenza among community-dwelling elderly. Studies of institutionalized elderly suggest vaccination is 50-60% effective in preventing hospitalization and pneumonia, and up to 85% effective in preventing death, even though efficacy in preventing the actual flu illness may be only 30-40% among the frail elderly.5 Furthermore, randomized controlled studies have found that health care staff vaccination reduces influenza-related morbidity and death among facility residents.6
Despite the influenza vaccination being recognized as the single most effective means of preventing or attenuating influenza for those at high risk, and NACI's ultimate goal to vaccinate at least 90% of all eligible people, only 70-91% of long-term care facility residents and 20-40% of adults and children with medical conditions receive vaccine annually. Studies of health care workers in hospitals and long-term care facilities have shown vaccination rates as low as 26%, ranging up to 61%.5 Many health care providers experience subclinical infection and thus continue to work, potentially transmitting infection to their patients. Low rates of utilization are due to both failure of the health care system to offer the vaccine, as well as fears about adverse reactions or skepticism of its efficacy or necessity. Health care providers have an important responsibility to help NACI reach its goals, as they often have great influence over whether or not a patient decides to be immunized. Furthermore, "in the absence of contraindications, refusal of health care workers to be immunized implies failure in their duty of care to their patients".5
- Canadian Consensus Conference on Influenza. Can Commun Dis Rep 1993;19:136-47.
- Health Canada, Population and Public Health Branch. Information Sheet on Influenza, November 2001.
- Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999;48(RR-04):1-28.
- Nicholson KG. Should staff in long-stay hospitals for elderly patients be vaccinated against influenza? Lancet 2000;355:83-4.
- National Advisory Committee on Immunization. Statement of influenza vaccination for the 2002-2003 season. Can Comm Dis Rep 2002;28(ACS-5):1-17.
- Carmen WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomized controlled trial. Lancet 2000;355:93-7.