Infection Control & Hospital Epidemiology (2018), 39, 955–960 doi:10.1017/ice.2018.115
Original Article
The effect of timing of oseltamivir chemoprophylaxis in controlling influenza A H3N2 outbreaks in long-term care facilities in Manitoba, Canada, 2014-2015: a retrospective cohort study
Davinder Singh MD1, Depeng Jiang PhD1, Paul Van Caeseele MD2 and Carla Loeppky PhD1 1Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada and 2Department of Medical Microbiology, Department of Pediatrics
and Child Health, University of Manitoba, Winnipeg, Canada Abstract
Objective: This study examined the effect of the timing of administration of oseltamivir chemoprophylaxis for the control of influenza A H3N2 outbreaks among residents in long-term care facilities (LTCFs) in Manitoba, Canada, during the 2014–2015 influenza season. Methods: A retrospective cohort study was conducted of all LTCF influenza A H3N2 outbreaks (n=94) using a hierarchical logistic regression analysis. The main independent variable was how many days passed between the start of the outbreak and commencement of oseltamivir chemoprophylaxis. The dependent variable was whether each person in the institution developed influenza-like illness (yes or no). Results: Delay of oseltamivir chemoprophylaxis was associated with increased odds of infection in both univariate (t=5.41; df=51; P<.0001) and multivariable analyses (t=6.04; df=49; P<.0001) with an adjusted odds ratio of 1.3 (95% confidence interval [CI], 1.2–1.5) per day for influenza A H3N2. Conclusions: The sooner chemoprophylaxis is initiated, the lower the odds of secondary infection with influenza in LTCFs during outbreaks caused by influenza A H3N2 in Manitoba. For every day that passed from the start of the outbreak to the initiation of oseltamivir, the odds of a resident at risk of infection in the facility developing symptomatic infection increased by 33%.
(Received 21 February 2018; accepted 23 April 2018; electronically published June 12, 2018)
Influenza is a major cause of morbidity and mortality in Canada, accounting for an estimated 12,000 hospitalizations and 3,500 deaths every year.1 It also disproportionately affects vulnerable populations, with the elderly being affected most severely.1 A proportion of elderly adults reside in long-term care facilities (LTCFs), which are particularly prone to outbreaks of influenza. Long-term care facilities are generally defined as institutions that
care for residents who are unable to take care of themselves; residents are typically over the age of 65 years.2 An outbreak is defined as an increased incidence of a disease compared to the background rate.3 Outbreaks contribute to the significant morbidity and mortality attributed to influenza; many of the residents in LTCFs havemultiple chronic conditions.4–8 Influenza is also known to exacerbate chronic medical conditions, specifically cardiac or pulmonary disorders, cancer, other immune compromising conditions, kidney disease,
Author for correspondence: Dr Davinder Singh, Department of Community Health
Sciences, University of Manitoba, S111-750 Bannatyne Avenue, Winnipeg, MB, Canada, R3E 0W3. E-mail:
umsing67@myumanitoba.ca PREVIOUS PRESENTATION: A preliminary study was published in 2016 in the
Canadian Journal of Infection Control. The current study is significantly larger with a more in-depth analysis Cite this article: Singh D, et al. (2018). The effect of timing of oseltamivir chemo-
prophylaxis in controlling influenza A H3N2 outbreaks in long-term care facilities in manitoba, canada, 2014-2015: a retrospective cohort study. Infection Control & Hospital Epidemiology 2018, 39, 955–960. doi:10.1017/ice.2018.115
© 2018 by The Society for Healthcare Epidemiology of America. All rights reserved.
anemia or hemoglobinopathy, diabetes or othermetabolic conditions, conditions that compromise the management of respiratory secre- tions, and morbid obesity.1 In Manitoba, if an influenza outbreak is detected in an
LTCF, the standard protocol is that all symptomatic residents receive 5 days of oral oseltamivir at the therapeutic dose and all other residents receive 10 days of oseltamivir chemoprophy- laxis at the prophylactic dose.9 This approach is described in many studies, is used in other countries, and is similar to the recommendations of the Infectious Diseases Society of America (IDSA).5,7,9–12 In the 2014–2015 influenza season, Manitoba administered
more than 50,000 doses of oseltamivir for LTCF outbreak chemoprophylaxis13 at $5.72 per dose.14 This one-season total of almost $300,000 does not include associated costs, such as nur- sing time, nor doses prescribed in the community or hospital settings. However, the use of prophylactic oseltamivir in the setting of LTCF outbreaks may not be warranted because the studies that the IDSA relied upon to make the recommendation for their use,6,8,11,15–17 and those published since the IDSA recommendation,5,7,12,18,19 have significant limitations, with low- quality evidence and mixed results. To better understand whether there is utility in following the portion of the IDSA guideline relating to oseltamivir use in LTCF
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