What is the purpose of vaccines

What you should know about vaccines

What are live vaccines?

Live vaccines contain pathogens that can still multiply, ie are "viable", but whose disease-causing properties have been bred. One speaks here of so-called attenuated pathogens. Examples are vaccines against mumps, measles, and rubella.

What are dead vaccines?

Inactivated vaccines contain killed, i.e. no longer capable of reproducing pathogens. This also includes vaccines that only contain components or individual molecules of these pathogens. Depending on the type of production and the degree of purification, one speaks of whole virus, split or subunit vaccines. Examples are vaccines against hepatitis A (whole virus) and influenza (split and subunit vaccines). (You can find detailed information on influenza vaccination on the website of the Robert Koch Institute)

What are vector vaccines?

Vector vaccines consist of viruses that are harmless to humans, so-called vectors. The vectors cannot reproduce in humans, or only to a very limited extent. In order for the human immune system to be able to build up the defense against the pathogen, it must come into contact with the pathogen's molecules (antigens). This can be achieved in a number of ways.

Either a molecule from the virus envelope of the vector can be exchanged for a molecule from the envelope of the pathogen in a vector.

Or the vector contains the information on the structure of one or more protein molecules (antigens) of the pathogen. This information is then read in the human cell, the antigen of the pathogen is produced and presented to the immune system. This triggers the immune response desired during vaccination.

When making these changes to the vector, care is taken to ensure that it is safe for humans and the environment.

An example of vector vaccines is the “Ervebo” vaccine against Ebola.

What are mRNA vaccines?

With these vaccines, no pathogens or their components (antigens) are required for immunization. Through the vaccination the cells in the muscle tissue are only given the information for the production of individual antigens in the form of an mRNA (messenger RNA or messenger RNA). Similar to an infection with a virus, the cell begins according to the blueprint of the mRNA with the production of proteins that are presented to the immune system as antigens and trigger an immune response. Since these are only individual proteins that are produced by the cells, there is no risk of infection with this method.

Can mRNA vaccines change the genome?

MRNA is a messenger molecule that cannot be incorporated into the DNA of a cell and is broken down relatively quickly by the body. A change in the genome, i.e. an impairment of the germ cells (egg cells or sperm), cannot take place.

Why are there so many different types of vaccines?

Different types of vaccines have different properties in terms of the immune response they trigger and they have different manufacturing requirements. The pathogens also have different properties, so that not all types of vaccine are suitable for all pathogens. Extensive tests are therefore carried out to determine which vaccines are best suited for a particular disease.

How are vaccines developed?

How is a vaccine developed?

What challenges do researchers face when developing a vaccine against a new virus? Our explanatory film shows the five phases.
Copyright: BMBF

Are Vaccines Safe?

Vaccinations are generally very safe. As a rule, they do not make you sick, nor can others be infected by people who have been vaccinated. Because most vaccines consist of weakened or inactive pathogens or components of pathogens. Often, however, the vaccinated people temporarily experience individual symptoms such as a high temperature or headache. These are signs that the body is actively dealing with the vaccine and is building up effective protection against the pathogen. In any case, these vaccine reactions are much less serious than the symptoms or consequential damage caused by the illness against which the vaccination is carried out.

With today's vaccines, permanent damage has only occurred in less than one in a million people vaccinated after a mumps or measles vaccination. For comparison: Unvaccinated people almost always get both diseases, and every tenth person with mumps also suffers from meningitis, every 500th person from measles also suffers from encephalitis. Both complications often leave permanent damage.

You can read more about the safety of vaccinations on the website of the Robert Koch Institute.

Is there a risk that the vaccine will transmit the disease it is supposed to protect against?

Basically, vaccines are designed and manufactured in such a way that they cannot transmit the disease they are designed to protect against.

Can I infect others if I have been vaccinated?

Since vaccines do not transmit the disease they are intended to protect against, it is also impossible to infect other people through vaccination alone. How well the vaccination then protects against infection and thus also prevents me from infecting others with the pathogen depends on the effectiveness of the vaccine.

What do you need adjuvants for?

A vaccine usually doesn't just contain antigens. Vaccine researchers have found that certain additives can significantly increase immunization, so-called adjuvants (from the Latin adjuvans = supporting). Some adjuvants trigger the body's own "alarm system" and thus trick the immune system into believing that pathogens have penetrated the body to a considerable extent. The sensors of this alarm system were found on the surface and inside of various immune cells. The immune system reacts to the alarm with increased intensity Activity, also with the multiplication of antibody-producing cells.

Aluminum hydroxide is the most commonly used adjuvant. For some years now, pharmaceutical companies have also been using special mixtures of fat-like molecules and water as adjuvants, which have an even stronger effect.

Vaccine researchers know from studies that adjuvants have three main effects:

  • Less antigen is sufficient for an immune reaction in the vaccinated person
  • It is less common that the vaccine does not work.
  • The vaccination protection is "broader", that is, the vaccination not only protects against the exact strain from which the antigens originate, but also against similar pathogens.

You can read more about this in the RKI's Impf-A-Z.

Am I 100% protected if I am vaccinated?

Some vaccines protect more than 98% of all vaccinated against disease. Other vaccines could only fully protect fewer people, but at least achieve such an immune protection in the others that the disease progresses more easily. It is important that many vaccinations have to be administered several times in order to achieve their full protective effect.

You can read more on this topic in the RKI's Impf-A-Z.