Active Vaccine Safety Surveillance — VAERS, EudraVigilance, and Beyond

Just as Module 7 distinguished passive spontaneous reporting from more proactive signal detection methods for conventional drugs, vaccine safety surveillance runs on a similar architecture, adapted for the population-scale, public-health context this module opened with. VAERS, the US Vaccine Adverse Event Reporting System jointly run by CDC and FDA, is the passive front door — open to anyone, patient or provider, to report a suspected AEFI. Like any spontaneous reporting system, it’s genuinely excellent at hypothesis generation and terrible at confirming causation on its own, for exactly the reasons Module 7 established: no reliable denominator, no control for who chooses to report, no built-in comparison group.

The Vaccine Safety Datalink addresses that gap directly, and it’s worth understanding as a preview of Module 15’s entire subject: it’s an active surveillance system built on a collaboration with large US healthcare systems, querying real, structured electronic health record data to conduct rapid, near-real-time safety studies rather than waiting for spontaneous reports to accumulate. This is exactly the kind of real-world-data-driven active surveillance Module 15 will cover in much greater depth — vaccine safety surveillance was, in many respects, an early and particularly mature adopter of exactly this approach, precisely because AESI monitoring (Lesson 14.3) depends on having a reliable background rate to compare against.

The EU runs vaccine-specific case handling and signal management through the same EudraVigilance infrastructure Module 7 introduced for conventional drugs, feeding into the same PRAC process Module 7’s Lesson 7.8 covered — vaccine AESIs get the same structured signal-management treatment as any other validated drug signal, just with vaccine-specific case definitions and background-rate comparisons layered on top. India’s PvPI has similarly strengthened its AEFI-specific integration substantially in recent years, with active surveillance pilot programmes building directly on the national ADR infrastructure Module 1 introduced.

The consistent theme across every system in this comparison, and the one worth carrying forward into Module 15, is that a genuine vaccine safety signal rarely rests on just one of these systems alone. A signal that shows up in passive VAERS or EudraVigilance reporting, and is then quantified through active surveillance data from something like the Vaccine Safety Datalink showing a genuine elevated observed-versus-expected rate, is a fundamentally stronger, more actionable finding than either source could produce independently — precisely the triangulation logic that runs through this entire course’s treatment of signal confirmation, from Module 7’s disproportionality work through to Module 15’s real-world evidence content.