Influenza A and B are the strains that most commonly infect humans, with subtypes of Influenza A H1N1 and H3N2 commonly circulating. H3N2 viruses can be associated with more severe disease and increased mortality.
Influenza occurs more often in the winter months and is spread easily from person to person. Complications of infection are more likely in the very young, older adults, pregnant women, and people who have certain health problems such as asthma or other forms of lung disease.
Rapid detection of influenza virus is important to guide effective treatment.