The protection: sophisticated preparation of the body's own defences

Day-to-day, the human body is equipped with an intelligent defence system, which can quickly identify foreign aggressors such as bacteria or viruses. This defence, the immune system, is engaged in a constant battle with harmful intruders, after which it stores away information about their outward appearance, much like a ‘wanted’ poster. This process, which helps the body to identify the pathogens should they reappear, takes place over several stages. First, the immune system recognizes foreign bodies using specific three-dimensional surface characteristics, known as antigens. Then, the body constructs complex protein molecules, the anti-bodies, which tackle and ideally paralyze the intruders. So that the immune system does not have to repeatedly fight the same pathogens from scratch, these anti-bodies are stored in so-called memory cells, like an archive of identikit photos. If an infection occurs again, the immune system will fall back on this system and recognize the pathogen immediately. In such a way, the immune system is able to react extremely quickly and destroy any harmful invaders, before the outbreak of illness.

Vaccination – exploiting a natural strategy

Vaccination uses exactly the same natural strategy to deliberately prepare the body’s own defences against a pathogenic attack. The word ‘vaccine’ originates from the Latin "vaccina", meaning "coming from cows". This designation stems from the discovery of a natural vaccination: Farm servants who had been earlier infected with the harmless cow smallpox were immune to the deadly human smallpox.

Meanwhile today there is an entirely different approach, in which vaccines are made up of viruses which are no longer infectious. Ultimately, vaccinations are not intended to make people ill, but to activate their immune system in such a way that it is nevertheless powerful enough to prevent an illness in the case of a viral attack. The development of vaccines against flu goes back many decades. After the flu virus was discovered for the first time in 1933, research establishments, above all those of the US military, began working on a vaccine. However, the first generation of flu vaccines in the early 50's consisted of crudely cleansed viruses, which resulted in a great deal of other illnesses and side-effects. In contrast, modern vaccines are highly optimized molecules, derived from dead, non-infectious viruses or small parts of viruses.

Flu vaccination.
Source: Novartis Behring

Flu: Every year a fresh vaccination recommended

Due to flu viruses’ transforming abilities, through ‘shifts and drifts’, vaccination against flu has to take place at least once a year, which is the only way to remain effectively immune to the viruses. Every year, for the new vaccine, the World Health Organization (WHO) selects the three virus strains which have caused the most cases of flu in the previous flu season. The selection is made using a complex system of stations, which are distributed across the globe. 112 centres in 83 countries annually announce their findings of the latest variants. In Germany, there are two national influenza centres working together with the WHO: The Robert Koch Institute in Berlin and the National Reference Centre for influenza Monitoring in Hanover. When the information has been gathered, a new vaccine is manufactured with a fresh composition for every new flu season. However, selecting these virus strains involves no small amount of prophecy - nobody can be completely sure exactly which strains will be the dominant agent behind the next wave of flu. The end result of this is that protection from flu by vaccination is never 100% certain.