Currently effective antivials for influenza treatment are two influenza viral neuraminidase inhibitors, oseltamivir (Tamiflu) and zanamivir (Relenza). Resistance to these drugs is reflected by reduced susceptibility of viral neuraminidase to these drugs. The hypothesis is that the signal ratio of two reagents (with or without a single concentration of the drug) correlates the IC50 value, an accurate measurement of drug resistance but impractical for clinical use.

The study design is to collect samples from participants. A portion of the sample is used for drug resistance detection using the test (QFlu Combo Test) under investigation. The remaining portion of the sample is used for culture. The culture positive samples are used for determination of IC50 values, which is used as a gold standard for defining whether a virus isolate is resistant to a drug or not. The sensitivity and specificity of the QFlu test will be calculated by comparing to the gold standard test.

Inclusion Criteria:

• Those who exhibit flu-like symptom(s) during a flu season and who (or whose guardians) are willing to participate in the study.

There are three population of participants: pediatric (in patient or out patient), in-patient (any age) and out-patient (any age).