​​​Established technologies:

  • ​Protein-based vaccines
    • ​Whole inactivated viral vaccines
    • Vaccines that are composed of one or more viral proteins (Subunit vaccines)
    • Virus-like particles (VLP)
    • Viral vector vaccines – non-replicating 
Technologies that have not been used previously for human vaccines:
  • mRNA vaccines
  • DNA vaccines
Below you can read more about the different vaccine technologies.​

Protein-based vaccines

Protein-based vaccines are composed of either whole inactivated (killed) virus, or one or more viral proteins. Inactivated virus or purified viral proteins cannot cause disease. The immune system recognises the viral components of the vaccine as foreign and induces primarily an antibody response to the virus which can contribute to providing protection against future infection. The majority of protein-based vaccines include an adjuvant that strengthens the immune response. Some adjuvants also allow for the induction of a T-cell response which is important to protect against severe disease. 

​Vaccines containing inactivated whole virus 

This technology is also used in polio vaccines and some influenza vaccines. 

Covid-19 vaccine candidates under evaluation that use inactivated whole virus:

Vaccines that contain one or more viral proteins (subunit vaccines)

This technology is also used in vaccines against hepatitis B and some influenza vaccines.

Approved subunit vaccines and vaccine candidates: 

Virus-like Particles (VLP)

These vaccines contain viral proteins that are arranged to resemble a viral particle, but the virus-like particle cannot replicate. Different cell types can be used to produce these vaccines. The virus-like particles cannot cause disease, but the immune system is stimulated to induce antibody responses that can contribute to combatting covid-19 in the event of a later infection. 

This technology is also used for the vaccine against HPV (human papillomavirus). 

Viral vectors – non-replicating

These vaccines are not made up of the covid-19 virus but use a different virus as a vector. The DNA genome in the viral vector is changed so that the viral vector cannot replicate, and its DNA encodes the spike protein of the covid-19 virus. The covid-19 vaccines approved so far that use this technology, use a common cold virus (from the adenovirus family) as a vector.

When the viral vector enters the host cell, the host cell machinery will use the information encoded in the DNA to produce the spike protein from the virus that causes covid-19. The spike protein does not cause disease, but the immune system will generate antibodies to the spike protein as well as prepare immune cells (T-cells) to combat covid-19 in the event of a later infection. 

Viral vectors for these vaccines are defined as gene modified organisms (GMO). Research has not indicated that these viral vector vaccines have the ability to induce changes in the genes of the vaccinated individual. As for all other vaccines, they are only transiently​ present in the body before they are broken down and removed by the immune system.

This technology has been used for some Ebola vaccines.

Approved covid-19 vaccines and vaccine candidates under evaluation that use non-replicating viral vectors:

mRNA vaccines

These vaccines contain messenger RNA (mRNA) which, once in the cell, can be used to make the spike protein of the virus causing covid-19. The mRNA is ‘packaged’ into small lipid particles to help the mRNA enter host cells. The cell's protein synthesis machinery is then used to make the spike protein. The spike protein does not cause disease, but the body will generate antibodies against the spike protein and prepare immune cells (T-cells) to combat covid-19 in the event of a later infection. 

This technology is new which is why vaccines based on this technology have not been approved previously.

Approved covid-19 vaccines that use mRNA technology: 

DNA Vaccines

These vaccines contain DNA (*) which codes for the spike protein of the virus causing covid-19.

The host cell uses the information encoded in the DNA to produce the spike protein. The spike protein does not cause disease, but the body will generate antibodies against the spike protein and prepare immune cells (T-cells) to combat the virus causing covid-19 in the event of a later infection. 

(*) The virus causing covid-19 (SARS-CoV-2) is an RNA virus. The DNA that is used in the vaccine is cDNA (complementary DNA). 

This technology is new which is why vaccines based on this technology have not been approved for use in humans previously.​

Adapted covid-19 vaccines

For information about  adapted versions of authorised covid-19 vaccines, see EMAs webpage​



Oppdatert: 18.11.2022

Publisert: 17.12.2020

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