Non-immunized nurses spark deadly flu outbreak
May 1, 1999 3 minutes read
MMWR Update
Non-immunized nurses spark deadly flu outbreak
Importance of HCW vaccination emphasized
An outbreak of influenza A in a long-term care facility that resulted in two deaths and three hospitalizations was sparked by flu infections in unvaccinated health care workers, the Centers for Disease Control and Prevention reports.
Because influenza infections can be severe in debilitated populations and because vaccine effectiveness is lower among residents (30%-40%) than in healthy adults (70%-90%), the CDC recommends that health care workers and others caring for high-risk patients receive influenza vaccine annually. Health care workers and family members should be educated about the potentially serious consequences of influenza illness for high-risk people and the need to limit contact with these people. When health care workers and family members are ill, they should avoid contact with high-risk people.
The first cases in the Santa Clara, CA, facility occurred during Dec. 21-Dec. 28, 1998, among five unvaccinated nurses who worked in two adjacent units in the same building. From Dec. 29, 1998, through Jan. 17, 1999, additional cases developed among residents and staff from those two units. Overall, 34 (11%) of 309 staff members and 25 (13%) of 192 residents were infected. Three residents were hospitalized and two died, including one who was not vaccinated because of a history of egg allergy.
Residents in the facility are assigned to different buildings according to the level of care required. The most debilitated residents, most of whom are bedridden and require complete care, resided in the building where the outbreak began. During the fall, residents in all four buildings received influenza vaccination unless contraindicated. Of the 1,200 staff members offered vaccine, only some 200 (17%) were vaccinated at the facility, though some may have been vaccinated by outside providers. Forty-nine of the 50 residents in the two initially affected units had been vaccinated before the outbreak, compared with 12 (26%) of the 47 staff members in those units. Outbreak-control measures included cohorting ill residents under droplet precautions and administering amantadine for prophylaxis and treatments. Unvaccinated staff were offered amantadine prophylaxis and influ enza vaccine. Ill staff were discouraged from coming to work, and ill visitors were asked to postpone their visits. Influenza outbreaks can occur among highly vaccinated long-term care populations even in years when the vaccine is well-matched to circulating virus strains, the CDC noted.
Long-term care facilities should conduct surveillance to identify clusters of respiratory illness and should alert state or local health departments when clusters are identified. Early detection of influenza outbreaks and timely initiation of control measures, such as cohorting of ill residents, use of droplet precautions, and use of antiviral medications for prophylaxis or treatment can limit the spread of disease. Amantadine and rimantadine are 70% to 90% effective in preventing influ enza A infections and can reduce severity and duration of symptoms from influenza A when administered within 48 hours of onset. However, these medications are not effective against influ enza type B viruses. Chronic care facilities should know which laboratories in their area perform rapid influenza A testing and should develop a plan to rapidly detect influenza A outbreaks and to administer antiviral medications if influenza is detected.
Reference
1. Centers for Disease Control and Prevention. Update: Influenza activity — United States, 1998-1999 season. MMWR 1999; 48:177-181.
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