Following the sudden and unexpected emergence of influenza A(H1N1)pdm09 (2009 H1N1) virus, this observational study was initiated to describe participants seeking medical care in geographically diverse locations with 2009 H1N1 infection and their clinical course over a 14-day period following enrollment. In 2011, as surveillance indicated that 2009 H1N1 virus was co-circulating with other seasonal influenza A and B viruses worldwide, the protocol was expanded to include other influenza A subtypes and influenza B viruses. This version of the protocol further broadens the scope of this observational study. With the recognition that novel respiratory viruses other than novel influenza A viruses, e.g., Middle East Respiratory Syndrome Coronavirus (MERS-CoV), could become prevalent and of major public health importance, the objectives of this protocol have been expanded
Inclusion Criteria: * Be ≥ 18 years of age * Have a signed informed consent by participant * Have a fever (37.8 degrees C (100 degrees F) or higher on examination or patient-reported fever (37.8 degrees C (100 degrees F) or higher, or feverishness (felt febrile but did not take temperature) in the past 24 hours. * Have a cough and/or sore throat * Have suspected influenza or a suspected targeted non-influenza viral respiratory infection Exclusion Criteria: \- Current imprisonment, or compulsory detention (involuntary incarceration) for treatment of a psychiatric or physical illness.