Using PCR as ` gold standard ' , Quidel Influenza A+B POCT detected 24.4 % [ 95 % confidence interval ( CI ) 16.0 % to 34.6 % ] of influenza infections ( specificity 99.7 % , 95 % CI 99.2 % to 99.9 % ) ; viral culture detected 21.6 % ( 95 % CI 13.5 % to 31.6 % ; specificity 99.8 % , 95 % CI 99.4 % to 100 % ) .