Detection of Nosocomial Influenza Outbreaks in Long-Term Care Facilities Through Active Laboratory Surveillance in New York City

Influenza is one of the leading causes of mortality in the elderly. 1 Thompson W.W. Shay D.K. Weintraub E. et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA. 2003; 289: 179-186 Crossref PubMed Scopus (3110) Google Scholar More than 90% of influenza deaths and 50% of hospitalizations occur in persons over age 65. 2 Arden N.H. Patriarca P.A. Kendal A.P. Experiences in the use and efficacy of inactivated influenza vaccine in nursing homes. in: Kendal A.P. Patriarca P.A. Options for the Control of Influenza. Alan R Liss, New York1986: 155-168 Google Scholar , 3 Patriarca P.A. Weber A.J. Parker R.A. et al. Efficacy of influenza vaccine in nursing homes: reduction in illness complications during an influenza A (H3N2) epidemic. JAMA. 1985; 253: 1136-1139 Crossref PubMed Scopus (315) Google Scholar Residents of long-term care facilities (LTCFs) are particularly vulnerable to influenza because of factors related to their underlying conditions and residence in a congregate setting. 2 Arden N.H. Patriarca P.A. Kendal A.P. Experiences in the use and efficacy of inactivated influenza vaccine in nursing homes. in: Kendal A.P. Patriarca P.A. Options for the Control of Influenza. Alan R Liss, New York1986: 155-168 Google Scholar , 3 Patriarca P.A. Weber A.J. Parker R.A. et al. Efficacy of influenza vaccine in nursing homes: reduction in illness complications during an influenza A (H3N2) epidemic. JAMA. 1985; 253: 1136-1139 Crossref PubMed Scopus (315) Google Scholar Attack rates can range from 5% to 20% in nonepidemic years to as high as 60% during epidemics, with case fatality rates exceeding 10%. 1 Thompson W.W. Shay D.K. Weintraub E. et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA. 2003; 289: 179-186 Crossref PubMed Scopus (3110) Google Scholar Outbreaks can occur even in the presence of high resident vaccination rates, because of the reduced efficacy of vaccination in the elderly due to impaired immune function. 4 Strassberg M.A. Greenland S. Sorvillo F.J. et al. Influenza in the elderly: report of an outbreak and a review of vaccine effectiveness reports. Vaccine. 1986; 4: 38-44 Crossref PubMed Scopus (140) Google Scholar But although vaccination in the elderly may not prevent influenza infection, it has been shown to reduce serious complications and deaths. 5 Jefferson T. Rivetti D. Rivetti A. et al. Efficacy and effectiveness of influenza vaccine in elderly people: a systematic review. Lancet. 2005; 366: 1165-1174 Abstract Full Text Full Text PDF PubMed Scopus (534) Google Scholar