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Article in Japanese

The effect of prior contraction of seasonal influenza A in comparison to influenza B on immunity to 2009 A/H1N1

Shouichi KATOH

The outbreak of the new strain 2009 A/H1N1 influenza virus in children who had contracted seasonal influenza A was compared with that of children who had contracted influenza B, with a relative risk (OR=0.5999; 95% CI: 0.4170-0.8628; p<0.005). There was age difference in rates of contraction during the 2009 A/H1N1 influenza outbreak with higher rate observed among children between the ages of 6 and 7 who had contracted influenza A. Additionally, it was noted that the outbreak rate in patients who had contracted seasonal influ-enza A was low in the early epidemic stage of this new strain and rose in the later stage. This study considers the possibility of cross-protective immunity induced by prior infection with seasonal influenza A.

Katoh Pediatrics

Key words
Received May 21, 2010
Accepted October 4, 2010

22 (4):369─379,2010