Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. There are 4 types of influenza viruses: types A, B, C and D. Influenza A and B viruses cause seasonal epidemics of disease.
Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. There are 4 types of influenza viruses: types A, B, C and D. Influenza A and B viruses cause seasonal epidemics of disease.