CALCA and coinfection: A previous study using a combination of CRP and PCT levels to evaluate bacterial co‐infections observed increased accuracy in differentiating children with bacterial co‐infections from those infected with H1N1 alone.10 Similar observations were reported in the present study, in which we used a multivariate logistic regression analysis to construct a new model using PCT and CRP levels: [Logit(P) = −1.912 + 0.546 PCT + 0.087 CRP].