PhD defence S. (Sammy) Huygens

Below is a brief summary of the dissertation: 

People with weakened immune systems, especially patients with hematological malignancies, are at a higher risk for infectious diseases, which often present with severe outcomes. COVID-19 is one of these infectious diseases. While vaccination was a crucial step in controlling the COVID-19 pandemic, the effectiveness of vaccination in patients with weakened immunity has proven insufficient. Alternative strategies include the administration of antibodies. In this thesis, we have demonstrated that administering antibodies from convalescent plasma or hyperimmune globulins does not provide adequate protection. Another strategy is to prevent severe outcomes of COVID-19, for which we can use various medications, including monoclonal antibodies, viral inhibitors, and convalescent plasma. We found that monotherapy carries a risk of viral mutations. We recommend applying combination therapy wherever possible, but further research is needed.

Moreover, individuals with hematological malignancies also face an increased risk of invasive fungal infections, which are associated with high morbidity and mortality. Diagnosing these infections poses significant challenges and impede timely treatment. In this thesis, we investigated the value of a new PCR test and a new galactomannan test. Additionally, we assessed the value of a baseline CT scan and a new technique based on next-generation sequencing. In summary, we conclude that a combination of different techniques is necessary to accurately assess whether a patient has a fungal infection.