Blood donor testing as a sentinel for emerging infections

Emerging infections are diseases that newly appear in a population or rapidly increase in incidence, geographic spread, or severity. Factors such as intensified human–animal interactions, climate change, conflict, and societal changes contribute to their emergence. Surveillance is therefore essential to detect changes in pathogen circulation early and support timely public health interventions. Sentinel monitoring is a surveillance approach that uses selected healthcare providers, laboratories, institutions, or populations to track specific pathogens or diseases. Although only a subset of cases is monitored, this method can provide early warning of emerging infections, new variants, or unexpected increases in disease activity. These signals allow health authorities to respond quickly and implement measures to reduce further spread.
Blood establishments routinely screen large numbers of donations for infectious agents but are rarely used for sentinel surveillance. Sanquin Blood Supply Foundation, responsible for the blood supply in the Netherlands, is well suited to support infectious disease monitoring. Donor participation requires minimal effort, while Sanquin’s automated infrastructure enables high-throughput screening and rapid scaling of testing. Also, a large archive of stored blood samples allows retrospective analyses. This thesis explored the potential of blood donor testing for sentinel monitoring of infectious diseases. We showed that blood donor populations can be used to evaluate diagnostic assays during pandemics, estimate seroprevalence following interventions such as vaccination campaigns, and assess the impact of emerging variants. Because many donors give blood repeatedly over time, they are particularly suitable for longitudinal studies, making blood banks valuable assets for infectious disease surveillance.