The Flu is a Master of Disguise

The flu virus mutates from one year to the next, deceiving the immune system. Even an annual vaccination cannot guarantee protection.

Influenza A is responsible for the worst flu epidemics. The virus type is particularly hazardous, as it exists in many versions, which all change from one year to the next to be able to escape the immune system.

On the surface of the virus particles, you will find the hemagglutinin (H) and neuraminidase (N) proteins. The proteins come in different versions, that name the virus – such as H1N1, which is the most common variant. But the virus proteins can mutate very fast, changing their appearance slightly. Every year, the body encounters a new version of flu virus, which the immune system has difficulty recognising and combating. That is because the antibodies which the body produces following an infection are customised to find specific areas on the H and N proteins, but the same details do not necessarily exist on the mutated variant.

Every year, doctors develop a vaccine, which is made to combat the virus variants which are found early in the season and consequently have the best chances of developing into epidemics. If the doctors choose the right flu versions, the vaccine protects well against the disease in that particular year, but it does not work the next year, when the viruses attack again in new disguises.