Hannah Chung1, Sarah A Buchan1,2,3, Aaron Campigotto4,5, Michael A Campitelli1, Natasha S Crowcroft1,3,6,7, Vinita Dubey3,8, Jonathan B Gubbay2,4,7, Timothy Karnauchow9,10, Kevin Katz11, Allison J McGeer3,7,12, J Dayre McNally9, Samira Mubareka13, Michelle Murti2,3, David C Richardson14, Laura C Rosella1,2,3, Kevin L Schwartz1,2,3, Marek Smieja15, George Zahariadis5,16, Jeffrey C Kwong1,2,3,6,17,18. 1. ICES, Toronto, ON, Canada. 2. Public Health Ontario, Toronto, ON, Canada. 3. Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada. 4. Hospital for Sick Children, Toronto, ON, Canada. 5. London Health Sciences Centre, London, ON, Canada. 6. Centre for Vaccine Preventable Diseases, University of Toronto, Toronto, ON, Canada. 7. Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada. 8. Toronto Public Health. 9. Children's Hospital of Eastern Ontario, Ottawa, ON, Canada. 10. Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, ON, Canada. 11. North York General Hospital, Toronto, ON, Canada. 12. Sinai Health System, Toronto, ON, Canada. 13. Sunnybrook Health Sciences Centre, Toronto, ON, Canada. 14. William Osler Health System, Brampton, ON, Canada. 15. McMaster University, Hamilton, ON, Canada. 16. Newfoundland & Labrador Public Health Laboratory, St. John's, NF&L, Canada. 17. Department of Family & Community Medicine, University of Toronto, Toronto, ON, Canada. 18. University Health Network, Toronto, ON, Canada.
Abstract
BACKGROUND: Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza. METHODS: Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-cause mortality following laboratory-confirmed influenza for community-dwelling adults aged >65 years during the 2010-2011 to 2015-2016 influenza seasons. RESULTS: Among 54,116 older adults tested for influenza across the 6 seasons, 6,837 died within 30 days of specimen collection. Thirteen percent (925 individuals) tested positive for influenza, and 50.6% were considered vaccinated for that season. Only 23.2% of influenza test-positive cases had influenza recorded as their underlying cause of death. Before and after multivariable adjustment, we estimated VE against all-cause mortality following laboratory-confirmed influenza to be 20% (95%CI, 8%-30%) and 20% (95%CI, 7%-30%), respectively. This estimate increased to 34% after correcting for influenza vaccination exposure misclassification. We observed significant VE against deaths following influenza confirmation during 2014-2015 (VE=26% [95%CI, 5%-42%]). We also observed significant VE against deaths following confirmation of influenza A/H1N1 and A/H3N2, and against deaths with COPD as the underlying cause. CONCLUSIONS: These results support the importance of influenza vaccination in older adults, who account for most influenza-associated deaths annually.
BACKGROUND: Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza. METHODS: Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-cause mortality following laboratory-confirmed influenza for community-dwelling adults aged >65 years during the 2010-2011 to 2015-2016 influenza seasons. RESULTS: Among 54,116 older adults tested for influenza across the 6 seasons, 6,837 died within 30 days of specimen collection. Thirteen percent (925 individuals) tested positive for influenza, and 50.6% were considered vaccinated for that season. Only 23.2% of influenza test-positive cases had influenza recorded as their underlying cause of death. Before and after multivariable adjustment, we estimated VE against all-cause mortality following laboratory-confirmed influenza to be 20% (95%CI, 8%-30%) and 20% (95%CI, 7%-30%), respectively. This estimate increased to 34% after correcting for influenza vaccination exposure misclassification. We observed significant VE against deaths following influenza confirmation during 2014-2015 (VE=26% [95%CI, 5%-42%]). We also observed significant VE against deaths following confirmation of influenza A/H1N1 and A/H3N2, and against deaths with COPD as the underlying cause. CONCLUSIONS: These results support the importance of influenza vaccination in older adults, who account for most influenza-associated deaths annually.
Authors: Mackenzie A Hamilton; Ying Liu; Andrew Calzavara; Maria E Sundaram; Mohamed Djebli; Dariya Darvin; Stefan Baral; Rafal Kustra; Jeffrey C Kwong; Sharmistha Mishra Journal: Influenza Other Respir Viruses Date: 2022-05-24 Impact factor: 5.606