Over the course of the past 4 years, the coronavirus SARS-CoV-2 (the virus that causes COVID-19) has spread all over the world. Although most people have built up immunity by now, people still regularly experience symptoms from new or previous infections. The expectation is that COVID-19 will not disappear, but will have an annual surge in autumn/winter. The question is why this is happening when so many Dutch people have been vaccinated or have previously had COVID-19.

RIVM is investigating immunity to SARS-CoV-2 among the general population in the Netherlands. In the PIENTER Corona study, we are collecting information about antibodies in the blood of the people who are participating. These antibodies indicate whether a person has been vaccinated or recently had a SARS-CoV-2 infection. By monitoring antibody levels in the PIENTER Corona participants, we learn more about how well people are protected against the virus and how long that protection lasts. RIVM is also collecting information about the number of people who have been in contact with the virus and have built up immunity following vaccination.

Not everyone becomes ill or develops severe symptoms from SARS-CoV-2. The symptoms are often mild, and sometimes people have no symptoms at all, but others have long-term symptoms after a SARS-CoV-2 infection. Most people who are infected with the virus will generate antibodies. Much of the general population in the Netherlands has been vaccinated against COVID-19, and many people have been vaccinated and also had a SARS-CoV-2 infection. Antibodies against the coronavirus are also generated after vaccination. RIVM is researching immunity among people of different ages throughout the Netherlands. The study provides important information about the development and duration of immunity to the virus among the Dutch population.

How does the study work?

The PIENTER Corona Study was launched in April 2020 with 3200 participants, and another 4500 participants were added in June 2020. Many of these 7700 participants have taken part in multiple rounds of the study by now. The research project was extended and new participants were invited in autumn 2021, joining the existing participants. As a result, it will be possible to, for example, monitor the duration of coronavirus immunity at all ages even more effectively.

The 12th round of the PIENTER Corona Study is expected to take place in spring 2024, while the 13th round is planned for autumn 2024.

Publishing results

After each round of research, RIVM publishes a summary of the results on the website. This always takes several months, since various steps are involved in the process leading from the start of a round to the final research results:

  • We invite participants to take part in a new round of research, and ask them to send in a blood sample and complete a survey. 
  • Within about a month, most of the blood samples have arrived at RIVM.
  • We examine the blood samples in the laboratory to check for antibodies and determine antibody levels. 
  • We perform quality checks on the laboratory tests.
  • The data from the completed surveys is processed into a database.
  • Then we compile the data from the surveys and the research data from the laboratory tests.
  • The definitive analyses and results are processed in scientific articles. Then a summary of the key results is published on the RIVM website.