http://www.bmj.com/content/342/bmj.c7297.full
free full text
Effectiveness of AS03 adjuvanted pandemic H1N1 vaccine: case-control evaluation based on sentinel surveillance system in Canada, autumn 2009
OPEN ACCESS
Next Section
Abstract
Objective To assess the effectiveness of the pandemic influenza A/H1N1 vaccine used in Canada during autumn 2009.
Design Test negative incident case-control study based on sentinel physician surveillance system.
Setting Community based clinics contributing to sentinel networks in British Columbia, Alberta, Ontario, and Quebec, Canada.
Participants 552 patients who presented to a sentinel site within seven days of onset of influenza-like illness during the primary analysis period between 8 November and 5 December 2009; participants were mostly (>80%) children and adults under 50 years old.
Interventions Monovalent AS03 adjuvanted pandemic influenza A/H1N1 vaccine as the predominant formulation (>95%) distributed in Canada.
Main outcome measures Vaccine effectiveness calculated as 1−(odds ratio for influenza in vaccinated (received pandemic H1N1 vaccine at least two weeks before onset of influenza-like illness) versus unvaccinated participants), with adjustment for age, comorbidity, province, timeliness of specimen collection, and week of illness onset. Sensitivity analyses explored the influence of varying analysis periods between 1 November and 31 December, receipt of trivalent seasonal influenza vaccine, and restriction to participants without comorbidity.
Results During the primary analysis period, pandemic H1N1 was detected by reverse transcription polymerase chain reaction in 209/552 (38%) participants; rates were highest in children and young adults (40%) and lowest in people aged 65 or over (9%). Among the 209 cases, 35 (17%) reported comorbidity compared with 80/343 (23%) controls. Two (1%) cases had received pandemic H1N1 vaccine at least two weeks before the onset of illness, compared with 58/343 (17%) controls, all single dose. Adjusted vaccine effectiveness overall was 93% (95% confidence interval 69% to 98%). High estimates of vaccine protection?generally at least 90%?were maintained across most sensitivity analyses.
Conclusions Although limited by a small number of vaccine failures, this study suggests that the monovalent AS03 adjuvanted vaccine used in Canada during autumn 2009 was highly effective in preventing medically attended, laboratory confirmed pandemic H1N1 illness, with reference in particular to a single dose in children and young adults.
What is already known on this topic
What this study adds
free full text
Effectiveness of AS03 adjuvanted pandemic H1N1 vaccine: case-control evaluation based on sentinel surveillance system in Canada, autumn 2009
- Danuta M Skowronski, epidemiologist12,
- Naveed Z Janjua, epidemiologist12,
- Gaston De Serres, epidemiologist3,
- Travis S Hottes, epidemiologist1,
- James A Dickinson, professor4,
- Natasha Crowcroft, director, surveillance and epidemiology56,
- Trijntje L Kwindt, research assistant/data coordinator1,
- Patrick Tang, medical microbiologist17,
- Hugues Charest, virologist3,
- Kevin Fonseca, clinical virologist8,
- Jonathan B Gubbay, medical microbiologist69,
- Nathalie Bastien, virologist10,
- Yan Li, virologist10,
- Martin Petric, clinical virologist17
- <address><sup>1</sup>British Columbia Centre for Disease Control, Vancouver, BC, Canada </address>
- <address><sup>2</sup>University of British Columbia, School of Population and Public Health, Vancouver </address>
- <address><sup>3</sup>Institut National de Sant? Publique du Qu?bec, 2400 d?Estimauville, Qu?bec, QC, Canada </address>
- <address><sup>4</sup>Departments of Family Medicine and Community Health Sciences, University of Calgary, Calgary, AB, Canada </address>
- <address><sup>5</sup>Ontario Agency for Health Protection and Promotion, Toronto, ON, Canada </address>
- <address><sup>6</sup>Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto </address>
- <address><sup>7</sup>Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver </address>
- <address><sup>8</sup>Alberta Provincial Laboratory, Calgary </address>
- <address><sup>9</sup>Ontario Agency for Health Protection and Promotion, Public Health Laboratory, Toronto </address>
- <address><sup>10</sup>Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, MB, Canada </address>
- Correspondence to: D M Skowronski, Epidemiology Services, BC Centre for Disease Control, 655 West 12th Avenue, Vancouver, BC, Canada V5Z 4R4 danuta.skowronski@bccdc.ca
- Accepted 22 November 2010
Next Section
Abstract
Objective To assess the effectiveness of the pandemic influenza A/H1N1 vaccine used in Canada during autumn 2009.
Design Test negative incident case-control study based on sentinel physician surveillance system.
Setting Community based clinics contributing to sentinel networks in British Columbia, Alberta, Ontario, and Quebec, Canada.
Participants 552 patients who presented to a sentinel site within seven days of onset of influenza-like illness during the primary analysis period between 8 November and 5 December 2009; participants were mostly (>80%) children and adults under 50 years old.
Interventions Monovalent AS03 adjuvanted pandemic influenza A/H1N1 vaccine as the predominant formulation (>95%) distributed in Canada.
Main outcome measures Vaccine effectiveness calculated as 1−(odds ratio for influenza in vaccinated (received pandemic H1N1 vaccine at least two weeks before onset of influenza-like illness) versus unvaccinated participants), with adjustment for age, comorbidity, province, timeliness of specimen collection, and week of illness onset. Sensitivity analyses explored the influence of varying analysis periods between 1 November and 31 December, receipt of trivalent seasonal influenza vaccine, and restriction to participants without comorbidity.
Results During the primary analysis period, pandemic H1N1 was detected by reverse transcription polymerase chain reaction in 209/552 (38%) participants; rates were highest in children and young adults (40%) and lowest in people aged 65 or over (9%). Among the 209 cases, 35 (17%) reported comorbidity compared with 80/343 (23%) controls. Two (1%) cases had received pandemic H1N1 vaccine at least two weeks before the onset of illness, compared with 58/343 (17%) controls, all single dose. Adjusted vaccine effectiveness overall was 93% (95% confidence interval 69% to 98%). High estimates of vaccine protection?generally at least 90%?were maintained across most sensitivity analyses.
Conclusions Although limited by a small number of vaccine failures, this study suggests that the monovalent AS03 adjuvanted vaccine used in Canada during autumn 2009 was highly effective in preventing medically attended, laboratory confirmed pandemic H1N1 illness, with reference in particular to a single dose in children and young adults.
What is already known on this topic
- Immunogenicity trials of AS03 adjuvanted pandemic H1N1 vaccines showed substantial vaccine induced antibody response after a single dose
- Interpretation of immunogenicity studies is limited by serological surrogates for protection, small sample sizes, and uncertain relevance if circulating viruses include an unrecognised mix of antigenic variants
What this study adds
- The effectiveness of the monovalent AS03 adjuvanted pandemic vaccine exceeded 90% against medically attended, laboratory confirmed pandemic H1N1 illness during autumn 2009 in Canada
- The results apply particularly to children and young adults
- Although limited by a small number of vaccine failures, results are consistent with the protection expected given very high vaccine induced antibody response and excellent match to circulating virus