Enhancing Post-market Monitoring

WHO is currently working to enhance post-market monitoring activities in order to further support equipment performance and reliability and to help strengthen national immunization programmes. A PMM Working Group is developing indicators, lessons learned, guidance and tools as well as is piloting a Cold Chain Equipment (CCE) Sentinel Surveillance programme in four countries.  

This effort is led by the PMM Working Group established in 2018 and tasked with guiding activities and aligning global efforts around strengthening PMM. The PMM Working Group is chaired by WHO and includes representatives from WHO (Prequalification and EPI teams), UNICEF (Programme and Supply Divisions), the Bill & Melinda Gates Foundation, the Gavi Secretariat, PATH, the Clinton Health Access Initiative, as well as independent experts.

The key activities of the PMM Working Group are:

  • roll out Sentinel Surveillance pilots in four countries
  • develop PMM terminology, performance indicators, data collection methodology, online tool and guidelines
  • develop lessons learned, including guidance and tools generated from the pilots, to generate a set of standards for PMM implementation that are scalable and can be embedded in country-level EPI management.

CCE Sentinel Surveillance Pilot

Development of a centralized, systematic mechanism for Sentinel Surveillance, for addressing the gap in quality feedback on equipment performance, is a key goal of the PMM Working Group. CCE Sentinel Surveillance is now being piloted.

Before this pilot, only a limited amount of actionable information on equipment performance had been successfully collected and shared across stakeholders. This was problematic because any gap in equipment performance feedback from country immunization systems can mean that poor equipment design and/or performance may go unnoticed and may therefore not be  addressed by WHO or equipment manufacturers. Yet WHO's vaccine coverage goals can only be achieved if vaccine storage equipment is reliable and performant, which in turn requires robust post-market monitoring. Sentinel Surveillance is aimed at facilitating corrective and preventive action to improve performance.

Pilot implementation

The PMM Working Group is piloting Sentinel Surveillance in four countries — Bangladesh, the Democratic Republic of Congo, Haiti and Pakistan — and representing four WHO regions (Africa, the Americas, the Eastern Mediterranean and South-East Asia) and a range of different brands and models of prequalified cold chain equipment.

In each of the four pilot countries WHO is working with a partner organization and the Ministry of Health, and building on existing country systems, to establish sentinel sites and set up a sustainable monitoring system for immunization equipment performance. Surveillance consists of monthly zero reporting on functioning and non-functioning equipment from each site based on a standard set of indicators and terminology and coupled with regular site visits for data verification. Root cause of failure analysis (using a methodology developed by PATH) is a key component of the pilot for any equipment reported to be non-functional. Whenever possible, the Surveillance Officer will be accompanied by local EPI technicians when visiting sites for failure analysis.

The Sentinel Surveillance approach has been selected for WHO PMM of vaccine refrigerators and freezers because it is proven to be rapid and cost-effective and yields high-quality results when implemented correctly. The relatively small investment, coupled with a low reliance on technology at the country level, and the availability of quality tools and guidance from WHO, means that the approach is more likely to be sustained after the end of the pilot period.

Using CCR performance data

Collecting CCE performance data via Sentinel Surveillance serves a dual purpose. At global level, it will provide WHO with comprehensive and consistent information about equipment, providing important insight into the reasons for equipment failure which can be fed into specifications and verification protocols, as well as into timely feedback to manufacturers to guide corrective and preventive actions. At country level, the systematic collection of performance data and root cause of failure analyses will provide valuable information that can be used to improve its vaccine management systems.

Long-term objective

An independent evaluation of the approach is planned, following which WHO will release PMM Sentinel Surveillance guidelines. The long-term objective is to integrate sentinel surveillance into national EPI programmes in all countries with a large investment in WHO-prequalified equipment.