Does the measles vaccine work

Vaccines - What Makes Them Different and How They Work

by Christiane Löll
Vaccines are the safest and most effective weapon against dangerous infectious diseases. But which vaccines and vaccination methods are suitable for when and for whom? An overview

Depending on the pathogen, different strategies are suitable for preparing the body for the fight against infection. At a active vaccination if a long-term protection is to be established, the vaccines contain killed pathogens or fragments of them, as well as weakened viruses. This triggers a reaction of the immune system, but not the disease itself, antibodies are formed, the production of which is increased in the event of a future encounter with the pathogen. It is often necessary to vaccinate several times until there is adequate protection.

In the passive vaccination it is a matter of building up rapid protection, the vaccines contain antibodies against the disease that viruses can fight directly. These are used, for example, if a vaccination has been missed, but there may have been contact with a pathogen, for example tetanus.

Live and dead substances

Offer particularly effective protection Live vaccines. However, they are not suitable for people with severely weakened immune systems. They contain the pathogens that are still capable of reproducing in a weakened form, in rare cases it can lead to a mild form of the disease. Live vaccines include, for example, those against measles, mumps, rubella and chickenpox.

Dead vaccines however, contain killed pathogens. Nevertheless, they provoke an immune reaction, as in the case of the rabies vaccination. Other vaccines mainly consist of components of the pathogen: proteins or sugars that are recognized by the immune system, one example is vaccination against hepatitis B. Other vaccines contain toxins that a pathogen releases when infected. They are rendered harmless using chemical processes, but trigger an immune response. Example: tetanus.

RNA and vector vaccines

Novel processes are intended to completely change vaccine production and also play a role in the search for protection against COVID-19. For one thing, there would be
RNA vaccines to call. During vaccination, for the first time, finished components of a pathogen are no longer administered, only the blueprints for them. They consist of RNA molecules, short copies of the genetic material. Our cells read out the RNA snippets and produce the pathogen's proteins themselves - and the immune system reacts to them. The body then becomes a kind of factory that makes its own vaccines.

Also on the agenda of researchers and the pharmaceutical industry are so-called Vector vaccines. One of the new vaccines against the dangerous Ebola fever belongs to this group. It was approved in the EU last autumn and is already being used in various African countries. It contains a harmless, reproductive ungulate virus (a vector virus) that produces a glycoprotein of the Ebola virus, it usually sits on its surface. The immune system then fights against this glycoprotein.

Vaccine against the SARS-CoV-2 virus

According to the World Health Organization (WHO), there are currently more than 40 vaccine candidates against the SARS-CoV-2 virus in development. They are based on different techniques. Almost all candidates are currently still in the preclinical development phase, which means that they have only been tested on cells and animals so far. Only two preparations in the USA and China are already being administered to patients; in these phase I studies of clinical development, among other things, the safety and tolerability of the substance are concerned. More developers want to follow suit soon.