Infection with the influenza virus is a serious disease. Influenza vaccination protects many people from the flu, or prevents it becoming more severe. As different strains circulate every year and these flu viruses can change during the flu season, vaccines need to be continuously adapted to ensure they provide effective protection. Professor Cichutek, President of the Paul-Ehrlich-Institut (PEI), explains in an interview how this works and why members of the public in Germany can rely on the safety, efficacy and quality of influenza vaccines.
Professor Cichutek: There are different influenza viruses that circulate during a season, and they can also change. We distinguish between influenza virus types with different subtypes and lines. In order for the influenza vaccine to contain the antigens (pathogen components) of the mainly circulating influenza virus strains for the respective season, the composition must be adjusted annually.
Professor Cichutek: The definition of the composition of influenza vaccines is the result of a multi-stage process, to which health experts from various international organisations contribute. The World Health Organization (WHO) makes an initial recommendation each year for the northern hemisphere and six months later for the southern hemisphere.
This recommendation contains what the antigen combination should look like, i.e. from which strains should antigens be represented in the vaccine. For the northern hemisphere, the recommendation is usually made in February on the basis of data collected worldwide by the international network of Essential Regulatory Laboratories, a laboratory network specialising in influenza viruses, which reports to WHO.
The experts working together in this network continuously monitor which virus strains are circulating and how they are changing over time. They study the genetic characteristics of circulating virus strains, their virulence and pathogenicity.
The Ad hoc Influenza Working Group of the European Medicines Agency (EMA) compares the vaccine composition recommended by WHO with the strains circulating in Europe. The working group usually follows the WHO recommendation.
Professor Cichutek: All influenza vaccines, like all other vaccines, require authorisation. Only when the influenza vaccine has successfully passed all stages of the medicinal product authorisation process, in which all data on quality, production, efficacy and safety are thoroughly tested, will it receive this authorisation. The medicinal product regulators evaluate the safety and efficacy of the influenza vaccine on the basis of non-clinical and clinical trials and data on adverse reactions, and only grant marketing authorisation if the benefit-risk profile is positive. The required quality and consistency of production must, of course, correspond to the state of the art in science and technology.
The composition of influenza vaccines usually changes every year. The various national EU authorities check before each vaccination season whether the strain composition for the individual influenza vaccines, as defined for the influenza season, has been correctly adopted. If the assessment is positive, they approve the strain adjustment. In Germany, this is done by the Paul-Ehrlich-Institut. Only flu vaccines with approved strain adjustment may be marketed.
In Germany, influenza vaccines, like all other vaccines, undergo official batch testing at the Paul-Ehrlich-Institut and, if the result is positive, receive official batch release before they can be put on the market.
It gives me great pride to point out that every year colleagues at the PEI carry out the inspection of the strain adjustment and the batch testing of the vaccines professionally, smoothly and quickly. The experts have already released around 21 million doses of vaccine for the 2019/2020 flu season.
Professor Cichutek: Essentially, we differentiate between influenza vaccines according to the type of production, the dosage form, the application in certain patient or age groups and the number of virus strains covered. In Germany, only tetravalent flu vaccines are available in the current 2019/2020 season. For example, the only influenza vaccine containing attenuated live influenza viruses is authorised solely for use in the 2 - 17 age group. It is also the only vaccine administered as a nasal spray. The Standing Committee on Vaccination (STIKO) at the Robert Koch Institute (RKI) in Berlin, on which an expert from the Paul-Ehrlich-Institut sits as a guest member, preferentially recommends this vaccine in cases where there are obstacles to injection.
Professor Cichutek: My personal recommendation is clearly yes, especially people who STIKO recommends should be vaccinated. The influenza vaccination should be carried out annually, because the vaccination effect decreases after a few months and, moreover, optimal protection against the expected virus variants can only be achieved with an annual strain adjustment. The vaccination also reduces the severity of the disease in cases where influenza occurs despite vaccination.
Professor Cichutek: No, you can't get flu from the flu vaccination. With the exception of a vaccine that contains attenuated live viruses, all flu vaccines are inactivated vaccines that cannot cause flu per se. And even the attenuated live vaccine cannot cause influenza. It consists of a live influenza virus that contains the antigens of the influenza virus types recommended by WHO, so that vaccine protection is built up against these different variants. The influenza virus used is so attenuated that it cannot cause influenza. Generally speaking, flu vaccines do not cause influenza.
Even if you can't get flu from the flu vaccination, under certain circumstances it is possible to get flu despite the flu vaccination. This can happen, for example, if the vaccination has taken place too late and the immune system has not yet built up complete protection. Our immune system needs about two weeks for effective protection. It is therefore important for the individual to be vaccinated before the flu viruses arrive in Germany. On the other hand, it can also happen if the immune system has not reacted sufficiently well to the vaccination. However, it has been shown that the disease will then be much milder than it would have been if the vaccination had not taken place.
The flu vaccination only protects against flu viruses, not against the many different cold viruses, some of which cause flu-like symptoms. If such a severe cold occurs in close proximity to the flu vaccination, it is often attributed to the flu vaccination - wrongly so.
Updated: 21.11.2019
