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Volume 18, Number 7—July 2012


Seroconversion to Seasonal Influenza Viruses after A(H1N1)pdm09 Virus Infection, Quebec, Canada

Mariana Baz, Jesse Papenburg, Marie-Eve Hamelin, Manale Ouakki, Danuta M. Skowronski, Gaston De Serres, and Guy BoivinComments to Author 
Author affiliations: Author affiliations: Centre Hospitalier Universitaire de Quebec, Quebec City, Quebec, Canada (M. Baz, J. Papenburg, M.-E. Hamelin, G. Boivin); Laval University, Quebec City (M. Baz, J. Papenburg, M.-E. Hamelin, G. Boivin); Institut National de Santé Publique du Quebec, Quebec (M. Ouakki, G. De Serres); British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada (D.M. Skowronski)

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Table A1

Seroconversion rates and GMTs for pandemic and seasonal influenza viruses, Quebec City, Quebec, Canada, 2009*

A(H1N1)pdm09 virus Age, y
Received seasonal vaccine in 2008–09 A/Quebec/147023/2009; A(H1N1)pdm09
A/Brisbane/59/2007 (H1N1)
A/New Caledonia/99 (H1N1)
A/Panama/2007/99 (H3N2)
Mean† Median (range) Seroconversion rate† GMT (95% CI) Seroconversion rate† GMT (95% CI) Seroconversion rate† GMT (95% CI) Seroconversion rate GMT (95% CI)
Positive, n = 67‡ 25.7 20 (7–61) 19 (28) 57 (85) 69.2 (49.9–95.9) 8 (12) 104.7 (73.5–149.1) 7 (10) 96.5 (65.5–142.4) 6 (9) 285.6 (188.5–432.6)
Negative, n = 55 31.2 35.5 (8–55) 13 (24) 0 5.9 (5.2–6.8) 1 (2) 41.0 (28.4–59.2) 0 34.4 (22.2–53.3) 3 (5) 124.4 (77.5–199.6)

*Values are no. (%) except as indicated. Seroconversion defined as an acute-phase serum titer of <10 with a convalescent-phase titer of >40 or a significant increase (>4-fold) in antibody titers between acute- and convalescent-phase serum samples. GMT, geometric mean titer;
‡A(H1N1)pdm09-positive persons were defined by positive reverse transcription PCR and/or seroconversion by microneutralization assay.

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