Post-authorisation surveillance of COVID-19 vaccines

All vaccines that become available on the Belgian market have been previously evaluated in clinical trials and have reached strict requirements in terms of quality, safety, immunogenicity (the vaccines’ ability to trigger an immune response), and vaccine efficacy (the vaccines’ ability to prevent a specific disease in a clinical trial setting). After roll-out of the vaccination campaign, it remains crucial to continue monitoring these indicators in what is called post-authorisation surveillance.

What is post-authorisation surveillance?

After authorisation (= when they become available on the Belgian market), all new vaccines continue to be monitored. The “post-authorisation surveillance” of COVID-19 vaccines is based on 5 pillars:

  • Evaluation of the vaccine  uptake (how many people have been vaccinated in a specific period of time) and vaccine coverage (the vaccinated proportion of a population) .
  • Measurement of the vaccine effectiveness (how well the vaccines work in preventing a certain outcome such as infection, illness or death).
  • Continuous monitoring of the vaccines’ safety.
  • Monitoring of vaccine acceptance (behaviours and beliefs surrounding the willingness of the population to get vaccinated)
  • Evaluation of immunogenicity (the ability of the vaccines to induce immune-responses) and seroprevalence (proportion of people with specific antibodies against the SARS-CoV-2 virus in their blood).

Why do we need post-authorisation surveillance of COVID-19 vaccines?

Vaccine acceptance, uptake and coverage studies shed light on how many people are willing to get themselves vaccinated and how many effectively do so. More specifically, vaccine coverage studies allow to estimate the proportion of vaccinated people in specific risk groups, such as the elderly or people with specific underlying disorders. These studies will give insight on attitudes towards vaccines in the population and will help identify gaps within the vaccination program that need to be addressed.

The monitoring of vaccine effectiveness, seroprevalence and immunogenicity allows us to assess the vaccine’s capacity to induce immune response and prevent infection both in the long-term and in the event of new circulating strains.

Finally, it is crucial to monitor the quality of the vaccines and to have a system in place capable of detecting late-onset or rare adverse events in order to continue to guarantee vaccine safety.

Overall, the results of post-authorisation surveillance are used to guide vaccine policy and to inform both health-professionals and the general population about the outcomes of Belgium’s COVID-19 vaccination program.

Sciensano plays an active role in the post-authorisation surveillance of the new COVID-19 vaccines by projects on vaccine uptake, effectiveness, safety, acceptance, seroprevalence (proportion of people with specific antibodies) and immunogenicity.

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