Vaccine Response Assessment in Children Using Dried Blood Spots: The DRIVE Study

BACKGROUND: Dried blood spots (DBS) are a minimally invasive alternative to serum for serological surveillance, but pediatric data remain limited, particularly in high-resource settings and in immunocompromised children. We evaluated the diagnostic accuracy of DBS for assessing vaccine-induced immunity in a pediatric cohort from Madrid, Spain. METHODS: This prospective observational study evaluated the diagnostic accuracy of DBS compared to serum samples in 134 children and adolescents (98 non-immunocompromised, 36 immunocompromised) at La Paz University Hospital (Madrid, Spain). IgG antibodies against six vaccine-preventable diseases-diphtheria, tetanus, pertussis, measles, mumps, and rubella-were quantified using the VirClia® IgG chemiluminescence assay. ROC curves were constructed to establish optimal DBS cut-off values for each pathogen. RESULTS: Using serum cut-offs, DBS showed sensitivities >95% and specificities >85% for all pathogens, except for pertussis, which had a sensitivity of 66.7%, and for rubella and mumps, which had specificities of 62.5% and 44.0%, respectively. Applying optimized DBS cut-offs improved specificity for rubella (81.2%) and mumps (88.0%). In immunocompromised children, sensitivity remained >80% for most pathogens but decreased for mumps (76.0%). Age and time since vaccination did not significantly affect DBS performance. CONCLUSIONS: DBS provide a reliable and practical approach for assessing vaccine-induced immunity in children and adolescents. Their ease of collection and transport make them especially valuable in settings with limited laboratory capacity. Population-specific cut-offs are essential, particularly for immunocompromised groups, to ensure diagnostic accuracy and support global immunization monitoring.