Patricia Kaaijk is a senior scientist at the Center for Immunology of Infectious Diseases and Vaccines. With her research she wants to gain more insight into the specific immune response induced after vaccination and natural infection with the aim to optimize the National Vaccination Program. 

After the corona pandemic, it has become clearer than ever that we can and must learn a lot about the defense against pathogens. We can implement this knowledge to combat infectious diseases using improved vaccination strategies


Research questions:

How does the immune response develop after vaccination and how does this compare with immunity after natural infection?

What types of specific immune cells directed against the mumps virus, the measles virus, or SARS-CoV-2 are induced after vaccination? Are the same frequency and type (subset and function) of immune cells generated after natural infection with these viruses? Are these immune cells able to protect us against disease and are they able to clear the virus after infection? How many antibodies are formed? How long do these antibodies persist and how well do they protect against disease or infection?

Why do some people get seriously ill after an infection and others don't?

Are there differences in the T cell response measurable between people who become seriously ill after an infection and people who recover spontaneously? This will be investigated for the pathogens: Borrelia bacteria, which can cause Lyme disease, and for SARS-CoV-2.


Patricia Kaaijk graduated as a biomedical scientist at Vrije Universiteit (1992). She obtained her PhD in 1996 at the University of Amsterdam on laboratory research on brain tumors. This research resulted in a bridge to the clinic by the initiation of a clinical study investigating a new treatment modality for patients with malignant brain tumors. In 1997, she started as a postdoctoral researcher at the Leiden University Medical Center, where she performed immunological research on tumor antigens. In 1999, she became a senior researcher at the VU University Medical Center, where she was project leader of research on brain tumors in children and investigated cytostatic resistance in children with acute leukemia. From 2003-2011 she worked as a senior regulatory affairs scientist at the former Netherlands Vaccine Institute. She became an expert in the registration process from vaccine concept to a registered vaccine. In 2012, she has become senior scientist (current position) conducting immunological research on various infectious diseases and conducting vaccine research to improve the National Immunization Program. She is member of the editorial board of the Infectious Diseases Bulletin.


  • Vaccinology
  • Immunology
  • Scientific writing



Key publications

Mumps infection but not childhood vaccination induces persistent polyfunctional CD8+ T-cell memory. de Wit J, Emmelot ME, Poelen MCM, van Binnendijk RS (respiratoir syncytieel), van der Lee S, van Baarle D, Han WGH, van Els CACM, Kaaijk P. J Allergy Clin Immunol. 2018 May;141(5):1908-1911.e12. 

A Third Dose of Measles-Mumps-Rubella Vaccine to Improve Immunity Against Mumps in Young Adults. Kaaijk P, Wijmenga-Monsuur AJ, van Houten MA, Veldhuijzen IK, Ten Hulscher HI, Kerkhof J, van der Klis FR, van Binnendijk RS. J Infect Dis. 2020 Mar 2;221(6):902-909. 

Genetic Analysis Reveals Differences in CD8+ T Cell Epitope Regions That May Impact Cross-Reactivity of Vaccine-Induced T Cells against Wild-Type Mumps Viruses. Kaaijk P, Emmelot ME, Kerkhof J, van Els CACM, Meiring HD, de Wit J, Bodewes R. Vaccines (Basel). 2021 Jun 25;9(7):699. 

Identification of Naturally Processed Mumps Virus Epitopes by Mass Spectrometry: Confirmation of Multiple CD8+ T-Cell Responses in Mumps Patients. de Wit J, Emmelot ME, Meiring H, van Gaans-van den Brink JAM, van Els CACM, Kaaijk P. J Infect Dis. 2020 Jan 14;221(3):474-482.

Children and adults with mild COVID-19: dynamics of the memory T cell response up to 10 months.  Kaaijk, P., Olivo Pimentel, V., Emmelot, M.E., Poelen, M.C.M., Çevirgel, A., Schepp, R.M.,  den Hartog, G., Reukers, D.F., Beckers,  L., van Beek, J.,  van Els, C.A.C.M., Meijer, A.,  Rots, N., de Wit, J. Front. Immunol. (2022)