Infection Prevention: Influenza: Epidemiology
Influenza is a serious disease:
- Influenza is the leading vaccine-preventable cause of death in the United States.
- It is estimated that 36,000 people die annually directly from influenza in the United States (1).
- 200,000 people are hospitalized annually in the United States due to influenza or its complications (2).
- Influenza has been associated with cardiovascular death in epidemiologic studies. In an autopsy study by Madjid and colleagues, the risk of death from acute myocardial infarction was increased by 30% during influenza epidemics in an essentially unvaccinated population (3). These authors estimate that influenza causes up to 92,000 annual deaths in the United States by triggering acute myocardial infarction (4).
Residents of long-term care facilities are particularly susceptible:
- Age- 90% of influenza-related deaths occur in persons over the age of 65 (1).
- Co-morbid medical conditions - conditions such as diabetes, heart disease, and lung disease increase the risk of complications from influenza. In one study, nursing home residents were three times as likely to be hospitalized for influenza than persons of similar age who did not live in nursing homes.
- Decreased immune response: Because of advanced age and other medical conditions, many long-term residents
are unable to mount an appropriate immune respone to infections such as influenza. In addition, vaccination may not be as effective in older individuals due to lack of immune response to the vaccine.
- Outbreaks - Because of close contact with other at-risk individuals, influenza can spread rapidly within a long-term care population. During outbreaks, 25-70% of residents can be affected, with fatality rates of 10-20% (5).
References:
1. Thompson WW, Shay DK, Weintraub E, Brammer L, Cox N, Anderson LJ, Fukuda K. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003; 289:179–186.
2. Centers for Disease Control Flu Facts
3. Madjid M, Miller CC, Zarubaev VV et al. Influenza epidemics and acute respiratory disease activity are associated with a surge in autopsy-confirmed coronary heart disease death: results from 8 years of autopsies in 34 892 subjects. Eur Heart Jrnl 2007.
4. Madjid M, Naghavi M, Litovsky S, Casscells SW. Influenza and cardiovascular disease: a new opportunity for prevention and the need for further studies. Circulation 2003; 108:2730–2736.
5. Smith PW, Rusnak PG. Infection Prevention and Control in the Long-Term Care Facility. Inf Control Hosp Epi 1997; 18(12): 831-849.
|
