Antiviral Control of Influenza in Aged-Care facilities in Sydney region over 3 seasons
Session I, V, or III – Booy, R.
Title of Contribution: Antiviral Control of Influenza in Aged-Care facilities in Sydney region over 3 seasons.
Author(s): Booy R1, 2, Heron L1, MacIntyre R3, Dwyer DE4, Yin J1, Lindley R5
Affiliation(s):
1 National Centre for Immunisation Research and Surveillance of Vaccine Preventable Disease, The Children's Hospital at Westmead and The University of Sydney, New South Wales, Australia;
2 Academic Unit of Child Health, Queen Mary's School of Medicine and Dentistry at Barts and the London, London, UK
3 School of Public Health and Community Medicine, Faculty, of Medicine, The University of New South Wales, Australia
4 Centre for Infectious Diseases and Microbiology Laboratory Services, Westmead Hospital, Sydney, New South Wales, Australia
5 Department of Geriatric Medicine, Discipline of Medicine, Westmead Hospital C24, The University of Sydney, Sydney, NSW, Australia.
Abstract:
Influenza outbreaks in Aged Care Facilities (ACFs) remain a significant cause of excess morbidity and mortality. They are frequently either underreported or not detected until after the opportunity has passed for optimal antiviral intervention. In the context of a cluster-randomized controlled trial, an active surveillance system for Influenza-like illness (ILI) including Point of care (POC) testing was established in 16 ACFs in Sydney, Australia, in mid-2006. The residents of the facilities are very frail and routinely have multiple co-morbidities.
A POC influenza rapid antigen test and laboratory direct immunofluorescence PCR and serology tests were used for diagnosis. Outbreak definition required a minimum of 2 ILI cases in 3 days or 3 in 7 days, where at least one tested positive for influenza. Following identification of an outbreak, depending on which arm the ACF was randomised to, residents and staff were either offered treatment with oseltamivir for symptomatic cases only or treatment as described plus prophylaxis to contacts in the facility.
Despite very high resident vaccination levels, we detected 9 outbreaks over the 3 seasons – this is more than an order of magnitude more frequent than is reported routinely to State health authorities. Six of the nine were randomised to treatment AND prophylaxis (TAP). The average duration of time in days from intervention to cessation of outbreak was 4.5 days for TAP ACFs (5 were 5 days or less) and 11.3 days in the 3 treatment only facilities (TOFs) (8, 11 and 15 days). The average number of deaths was 1.7 and 3.0 respectively. The average number of cases in TAP ACFs was 15.0 compared with 30.6 in TOFS. However, this is confounded by 2 of the outbreaks in TOFs being recognised much later in their course. Formal analysis will be presented taking into account design and other effects.
Oseltamivir was prescribed to 63/255 (25%) residents and to 18/216 (8%) members of staff in the 3 TOFs, while in the 6 TAP ACFs 49/397 (12%) residents were treated and another 262 residents (66%) were prophylaxed; 21/361 (6%) staff were treated and a further 190 (53%) received prophylaxis. No serious adverse events were associated with use of oseltamivir. Nineteen deaths occurred due to influenza; 9 were being treated with oseltamivir but in none was its use implicated in the death. No resistance has been detected.
