Do delays in data availability limit the implementation of near real-time vaccine safety surveillance using the Clinical Practice Research Datalink?

Removing delays in data availability is insufficient to significantly improve the performance of a NRTVSS system using CPRD. Expansion of CPRD data is required. KEY POINTS The Clinical Practice Research Datalink (CPRD) can be used to implement near real-time vaccine safety surveillance, but there is limited power to detect signals for rare outcomes. Delays in recording outcomes and in receiving data might limit power and timeliness of a system. We assessed the influence of these sources of delays to inform data providers of the steps required to improve a system using CPRD data. Removing delays in recording outcomes and receiving data is unlikely to significantly improve the performance of a system using CPRD data. Expansion of the data available is needed.