Guidelines on verification of measles elimination in the Western Pacific Region
The Western Pacific Region has made remarkable progress towards measles elimination since establishing the goal in 2003. Concerted efforts around the Region have substantially reduced measles cases by 93% between 2008 and 2012. Measles incidence was at a historic low in 2012, with 5.9 cases per million population. As many as 33 countries and areas (including the 21 countries and areas of the Pacific islands) may have interrupted measles virus transmission, and many are likely ready for verification.
At its sixty-first session in 2010, the Regional Committee for the Western Pacific urged the Regional Director to establish independent regional verification mechanisms for measles elimination. Furthermore, in 2012, the Regional Committee requested Member States to establish national verification committees (NVCs) to develop regular progress reports for submission to the Regional Verification Commission (RVC). Regional verification mechanisms (including verification principles, processes, structure, criteria and lines of evidence) will enable acknowledgement of countries and areas that have eliminated measles and provide guidance to those that have not yet achieved the goal.
These guidelines were developed based on the shared experiences from and consultations with WHO Member States. A consultation on verification of measles elimination in the Western Pacific Region was held in Manila, Philippines, in June 2010, and another consultation between the Regional Verification Commission and Member States took place in April 2012 in Manila, Philippines. Definitions of measles elimination and other essential concepts are provided, and core principles are enumerated. The core principles include the independence of the verification process led by the RVC and NVCs at regional and national levels, respectively. The RVC has the discretion to apply alternative evidence of elimination in place of recommended evidence and indicators for countries that are unable to provide complete data to assess standard indicators.
Three criteria and five lines of evidence presented below form the basis of verification. The three criteria are:
- documentation of the interruption of endemic measles virus transmission for a period of at least 36 months from the last known endemic case;
- the presence of verification standard surveillance; and
- genotyping evidence that supports the interruption of endemic transmission.
The five lines of evidence are:
- a detailed description of the epidemiology of measles since the introduction of measles vaccine (and rubella vaccine where applicable) in the national immunization programme;
- quality of epidemiological and laboratory surveillance systems for measles;
- population immunity presented as a birth cohort analysis with the addition of evidence related to any marginalized and migrant groups;
- sustainability of the national immunization programme including the resources for mass campaigns, where appropriate, in order to sustain measles elimination; and
- genotyping evidence that supports interruption of measles virus transmission.
Specific indicators or types of evidence are suggested under each line of evidence. Progress towards elimination will be judged against these five lines of evidence.
The structures and membership of the RVC and NVCs are described, as well as standard mechanisms for verification of elimination through a description of RVC and NVC functions and terms of reference. These include normative, advisory and verification functions, and for the chair, management functions. Advocacy functions are also included in the terms of reference for the RVC and NVC.
NVCs will ensure the development of annual progress reports and coordinate submissions to the RVC so that the RVC may verify both progress towards measles elimination and continued achievements. The progress towards elimination should be verified using the same lines of evidence presented in this document. It should be noted that the verification of national measles elimination and progress towards elimination are to be conducted annually until global measles eradication is achieved.
For countries that have already achieved measles elimination, post-verification needs are described. These include maintaining high levels of population immunity, verification standard epidemiological and virological surveillance, and preparedness plans for outbreak response.