Amsterdam institute for Immunology and Infectious diseases

The recent resurgence of measles in the Netherlands underscores the serious risks that vaccine-preventable diseases pose to immunocompromised individuals. Patients with impaired immune function, whether due to cancer, autoimmune disease, or other underlying conditions, remain highly susceptible to severe outcomes, even when standard prophylactic measures are followed. In such populations, the absence of antiviral immunity can render infections fatal, illustrating the critical importance of maintaining high vaccination coverage in the population.

Prof. Hazenberg highlights the need for research on vaccine responses in immunocompromised populations: ‘Pharmaceutical companies tend to prioritize studies that demonstrate vaccine efficacy in the general population, often avoiding the inclusion of immunocompromised individuals due to potential risk.’

Advances in hematology, oncology, and immunology have increased survival rates for patients with conditions that compromise immune function. However, these individuals often remain vulnerable to infections over prolonged periods. Dr. Bos emphasizes that ‘while more patients are surviving these conditions, they remain immunocompromised and susceptible to infections despite receiving appropriate prophylactic therapies and vaccinations.’ Measles is a vaccine-preventable disease; however, live-attenuated vaccines cannot be administered to severely immunocompromised patients. As a result, declining vaccination rates in the general population, and the subsequent increase in viral circulation, directly endanger these high-risk groups.

Research gaps and priorities

The case underscores multiple critical research gaps. Dr. Bos points out the urgent need to restore population-level vaccine coverage, while Prof. Hazenberg adds that ‘other unmet medical needs relate to immune reconstitution pathways, preservation of immunity despite therapy for malignancies and autoimmune diseases, and better therapies for devastating viruses like measles.’ Severe measles infection, for example, induces tissue damage, excessive inflammatory cytokine production, and immune cell dysregulation. Current research in intensive care and immunology seeks to develop diagnostic tools that monitor tissue-protective processes and antiviral immune responses, with the aim of balancing these competing phenomena.

Vaccination and preventive strategies

Prof. Hazenberg highlights the need for research on vaccine responses in immunocompromised populations: ‘Pharmaceutical companies tend to prioritize studies that demonstrate vaccine efficacy in the general population, often avoiding the inclusion of immunocompromised individuals due to potential risk.’ The COVID-19 pandemic illustrated how targeted research could improve outcomes: prospective cohort studies in immunocompromised populations, including individuals with HIV, malignancies, autoimmune diseases, inborn errors of immunity, and other conditions, informed vaccination guidelines and helped establish correlates of protection. Similar approaches are needed for other pathogens, including measles, to determine safe exposure levels and to guide social and occupational reintegration.

'Even with the best precautions, immunocompromised patients remain highly vulnerable when vaccine coverage in the community is low.'

Lieuwe Bos

Principal investigator and pulmonologist-intensivist in training

Translational approaches and passive immunization

Passive immunization represents a promising preventive strategy for patients who cannot receive live-attenuated vaccines. Prof. Hazenberg points to recent successes with monoclonal antibodies: ‘The introduction of nirsevimab has significantly reduced both the incidence and hospitalization rates associated with severe RSV infection in infants, highlighting the potential of passive immunization as an effective preventive strategy.’ Development of a broadly neutralizing antibody against measles could provide essential protection for immunocompromised patients currently at risk due to insufficient population-level immunity.

Ethical and societal considerations

Prof. Hazenberg: ‘As a hematologist, I frequently encounter skepticism regarding vaccination and viral infections in my clinical practice, particularly during the autumn season when I recommend influenza and COVID-19 vaccinations to patients.’ Understanding the underlying reasons for vaccine hesitancy is crucial. While misinformation is a common driver of distrust, religious beliefs and other personal considerations also contribute.

Furthermore, declining vaccination coverage raises ethical questions about balancing individual freedoms with public health responsibilities. Prof. Hazenberg observes that ‘it is deeply concerning that, despite the availability of safe and effective vaccines, these viruses are re-emerging. As clinicians, it is difficult to reconcile that parental decisions not to vaccinate place not only their own children but also immunocompromised individuals at risk.’

Immunocompromised patients are at risk not because of their own choices but due to the vaccination decisions of others. Mandatory childhood vaccination policies, for school or daycare entry, while ethically debated in some countries, can significantly reduce exposure risk for vulnerable populations. Prof. Hazenberg: 'During my postdoctoral training in the United States, for example, California law required our child to be vaccinated against varicella before attending daycare. For our family, this posed no issue, but others may view such regulations as an infringement on personal autonomy.’

This raises a fundamental ethical question: can individual freedom be upheld when it compromises the health and safety of others? Balancing personal liberties with public health responsibilities remains a complex societal challenge. Interdisciplinary research combining medicine, social psychology, and communication science is critical to better understand vaccine hesitancy and rebuild public trust.

'Continuing to study infections that are no
longer common is crucial to protect the most vulnerable.'

Mette Hazenberg

Professor in Hematology and Cell Therapy

Implications for researchers and clinicians

The re-emergence of measles emphasizes the necessity of maintaining awareness for diseases once considered eliminated. It also highlights the importance of continuing research on underexplored infectious diseases, particularly regarding immunocompromised populations. Advancing both basic and translational research on immune responses, vaccination strategies, and passive immunization can inform preventive measures, reduce morbidity and mortality, and guide evidence-based public health interventions.

Text: Esmée Vesseur, Lieuwe Bos and Mette Hazenberg