The seasonal and pandemic vaccines registered in Europe contain an inactive (killed) virus or only its external proteins. So they cannot cause flu, because such a virus is incapable of infecting it. They are given by injection into a muscle.
The composition of seasonal flu vaccines is updated annually on the basis of WHO recommendations and at least one of the 3 types of virus they are produced from is changed to optimize the effectiveness of vaccination in the coming season. The registration of any vaccine by the European Medicines Registration Agency (EMEA) is a guarantee that the product is safe enough to be used in the European Union.
Seasonal flu vaccines have been produced and used for almost 60 years. Clinical trials and observations after the administration of hundreds of millions of doses have proven that they are safe for children, adults, pregnant women, chronically ill and even immunocompromised people. The most common side effects proven to be related to the administration of the vaccine include:
1) local reactions (about 65% of vaccinated people): pain, redness and swelling at the injection site – usually mild, spontaneously resolving within 1-2 days;
2) general reactions (less than 15% of vaccinated persons) – mild fever, malaise, headache, pain in muscles and joints; the symptoms are mild and disappear after 1-2 days. Systemic reactions are more common in young children and people who are vaccinated against influenza for the first time.
Vaccines against A / H1N1v pandemic influenza they are constructed according to the same principle and produced according to a similar technology as the seasonal flu vaccines (the process is similar to changing the type of virus in a vaccine every year). The bodies of experts, international organizations (WHO, ECDC) and regulatory agencies (e.g. European EMEA, US FDA) therefore expect a similar safety profile. It was also indicated by clinical trials of currently registered and previously prepared pandemic vaccines (against avian influenza A / H5N1), carried out in several thousand people (mainly adults and the elderly). The only difference was the higher incidence of the mild local and general vaccination reactions described above after adjuvanted pandemic vaccines (see below). Clinical trials of currently approved pandemic vaccines in children – especially the youngest – are not yet complete and additional observations are ongoing in a larger population. During registration, however, the results of previous studies of A / H5N1 avian influenza vaccines in children from 6 months of age and from 3 years of age were used. Except for the type of virus, they were of the same composition as the A / H1N1v vaccines registered today. However, no studies of pandemic vaccines against influenza in pregnant women have been conducted, but preliminary observations from countries that have already started mass vaccination campaigns revealed no alarming or unexpected signals. Vaccination of pregnant women also protects their children from getting sick in the first 6 months of life.
Sterility-preserving adjuvants in some pandemic vaccines (see below) and adjuvants – are officially registered vaccine ingredients. They have been used in other vaccines for many years and are proven to be safe (see below).
Many institutions in Europe (EMEA, ECDC), around the world (WHO) and in individual countries where mass vaccination against pandemic influenza is taking place, closely monitor vaccine safety and cooperate with the system of early detection and warning against possible serious side effects. To date, several million doses of EMEA (and third-party) approved pandemic flu vaccines have already been administered in many countries, and no alarming signals have been recorded. These observations confirm previous experts’ assumptions and scientific data that the safety profile is similar to that of seasonal flu vaccines. There were also no reports of serious side effects in pregnant women.