“Is influenza an infectious disease?”

Highly infectious

Influenza is a virus that is transmitted in the air by droplets. The vaccine is 20 to 40 percent effective in prevention, but may also reduce severity when it is not fully successful.

Yes, influenza is a viral infectious disease that is highly communicable through respiratory transmission (droplets from sneezes and coughs and contaminated surfaces) with respiratory infection of those contaminated by the virus. Pneumonia secondary to flu is often not due to the flu virus, but rather to a secondary bacterial infection. Pneumonia with flu should be treated with both anti-virals and antibiotics. The flu vaccine should be taken every year; however, this year it is not very effective since the
predominant circulating strain (H3N2) is genetically different than the H3N2 strain in the vaccine.

Influenza or also called the common flu is a viral infection that is transmitted through droplets that may be carried through the air, for example, sneezing, coughing from an infected person to another one. Can also be transmitted from contaminated surfaces. So hand washing is important and wearing face masks that will not allow the droplets from an infected person to be spread from sneezing and coughing.
For this year's circulating influenza strains, the vaccine is not fully protective against one of the strains of influenza covered by the vaccine and we are seeing more cases despite vaccination. This is not uncommon specifically for the influenza vaccine that is developed for each annual season with some uncertainty about the major strains of influenza that will circulate in the future.

There are some peer reviewed publications that found evidence that the aerosol route is an important mode of transmission of influenza A virus and may be important for influenza B virus. There is still some controversy but evidence of viral contamination on surfaces, and in the air are both important modes of transmission for influenza virus.