Progress Toward Measles Elimination — Pakistan, 2000–2018

Immunization Activities

MCV1 was introduced in the routine childhood immunization schedule nationwide in Pakistan in 1974 (4), and MCV2 was added to the schedule in 2009. The doses are administered to children at ages 9 and 15 months. Administrative vaccination coverage^¶ data are reported each year from all districts** in Pakistan to the National Immunization Programme, where they are aggregated and reported to WHO and the United Nations Children’s Fund (UNICEF) through the Joint Reporting Form. WHO and UNICEF use reported administrative coverage and available survey results to generate annual estimates of vaccination coverage through routine immunization services (5). Estimated MCV1 coverage in Pakistan increased from 57% in 2000 to 76% in 2017, and estimated MCV2 coverage increased from 30% in 2009 to 45% in 2017 (Figure). A Demographic and Health Survey implemented nationwide during 2017–2018 estimated MCV1 and MCV2 coverage at 73% and 67%, respectively. Among the eight provinces and federal areas, survey estimates of MCV1 and MCV2 coverage were highest in Punjab (85% and 82%, respectively), Islamabad (83%, 77%), and Azad Jammu and Kashmir (83%, 75%); intermediate in Gilgit-Baltistan (66%, 62%), Khyber Pakhtunkhwa (63%, 50%) and Sindh (61%, 60%); and lowest in the Federally Administered Tribal Areas (35%, 21%) and Balochistan (33%, 34%) (6).

During 2005–2018, approximately 232.5 million children received MCV during SIAs (Table 1). A nationwide catch-up SIA was conducted in five phases during 2007–2008 and reached 66.6 million children aged <15 years with >100% administrative coverage documented. Following extensive flooding in the Indus River Basin in 2010, affecting much of Khyber Pakhtunkhwa, Punjab, and Sindh Provinces, subnational measles SIAs were conducted during 2010–2011 for children aged <13 years in flood-affected areas and aged <5 years in other areas; 29.7 million children were vaccinated (94% administrative coverage). In response to a measles epidemic in 2013, a nationwide SIA was conducted in phases during 2014–2015, and 61.4 million children aged <10 years were vaccinated (103% administrative coverage). An independent post-SIA coverage survey conducted in Sindh Province estimated 83% coverage. In response to a measles epidemic during 2017–2018, a nationwide SIA was conducted in 2018, and 37.1 million children aged <5 years (children aged <7 years in Punjab Province) were vaccinated; an independent post-SIA coverage survey estimated that SIA coverage was 93.3% overall and 95.7% in Punjab. Monovalent measles vaccine was used in all SIAs.

Surveillance Activities and Measles Incidence

Aggregated measles cases^†† are reported by all health facilities in Pakistan through the National Health Management Information System and reported annually through the Joint Reporting Form. In 2009, case-based measles surveillance^§§ was initiated in Pakistan following WHO Regional Office for the Eastern Mediterranean guidelines and using the existing vaccine-preventable diseases surveillance system with some modification (7). During 2013–2018, the case-based surveillance system was expanded to include additional health facilities; as of 2018, there were 7,555 reporting units. WHO technical officers were appointed in every province and area in the country during 2017–2018 to monitor key surveillance performance indicators.^¶¶ Reporting of measles virus genotyping to the WHO global measles nucleotide surveillance database was begun in 2007 (8).

After implementing nationwide catch-up measles SIAs during 2007–2008, the number of confirmed measles cases decreased from 7,641 in 2006 to 863 in 2009 (Figure). Following extensive flooding and large-scale population movements in 2010, the number of measles cases increased approximately eightfold, from 4,321 in 2010 to 40,923 in 2013, corresponding to an incidence of 230.3 per million. Following SIAs during 2013–2014, the number of confirmed cases declined to 4,112 in 2015, but increased to 33,007 in 2018 (incidence = 153.6 per million); the majority of these cases occurred before the nationwide SIA conducted in October 2018 (Figure) (Table 2). Overall, measles incidence averaged 24.6 cases per million population during 2000–2009, and 80.4 per million during 2010–2018.

During 2017 and 2018, the rates of suspected cases discarded after investigation were 2.1 and 1.5 per 100,000 population, respectively (Table 2). During 2007–2018, measles virus genotype results were obtained for 201 confirmed measles cases (50 D4, 150 B3, and 1 H1). D4 genotypes were found during 2007–2013, and B3 genotypes predominated during 2011–2018 with spread of B3 globally during 2010–2018.

Discussion

During 2000–2017, MCV1 and MCV2 coverage in Pakistan increased substantially, to 76% and 45%, respectively, but remained well below the WHO-recommended level of ≥95%. In addition, large-scale measles outbreaks occurred during 2012–2014 and 2016–2018, revealing coverage gaps from both routine immunization services and SIAs. The 2017–2018 Demographic and Health Survey found that coverage with all basic vaccines (1 dose of Bacille Calmette-Guérin [BCG] vaccine, 3 doses of diphtheria and tetanus toxoids and pertussis [DTP] vaccine, 3 doses of polio vaccine, and 1 dose of measles vaccine) ranged from 80% among children in the highest wealth quintile to 38% among children in the poorest wealth quintile and from 71% among children residing in urban areas to 63% among those in rural areas (6). To reduce disparities, increase vaccination coverage, and achieve measles elimination, enhanced efforts are needed to reach all children, particularly those in rural areas and poor communities. Periodic high-quality SIAs conducted according to WHO SIA guidelines, using the WHO SIA readiness assessment tool to ensure ≥95% 2-dose coverage, will require availability of adequate resources for success. For the 2018 SIA, Gavi, the Vaccine Alliance, provided funding support, and WHO, UNICEF and other international partners contributed to SIA planning, implementation, and monitoring. A postcampaign survey documented 93.3% coverage nationally, demonstrating the potential impact that appropriately funded and well-executed activities can have on improving SIA quality.

Case-based measles surveillance was introduced in 2009 and strengthened during 2017–2018. Some of the apparent increase in measles cases, especially during 2013–2018, reflects improved surveillance sensitivity. Nonetheless, WHO standard surveillance indicators reflected underreporting and low sensitivity of case detection overall. To increase case-based surveillance sensitivity to achieve measles elimination, case-based surveillance reporting sites need to be expanded to all health facilities in the country. High-quality nationwide case-based surveillance data are essential for identifying subpopulations with measles susceptibility in need of SIAs.

Pakistan remains one of only three countries worldwide that has never interrupted wild poliovirus type 1 transmission (9); therefore, polio eradication activities remain intense in the country. Measles elimination efforts can leverage the polio assets, experience, and capacity to identify and reach communities not accessing routine immunization services; engage local leaders and community members to ensure that all children in the target age groups participate in SIAs; use epidemiologic investigations to identify areas that need additional SIAs; and improve outbreak preparedness and response to rapidly contain outbreaks.

The Eastern Mediterranean Regional Technical Advisory Group on Immunization (RTAG) recommended forming a multipartner taskforce to apply lessons learned from the polio eradication initiative to address gaps in measles vaccination coverage. These include mapping areas where children missed by routine immunization services reside, identifying reasons for being missed, and developing a strategic plan that includes allocation of necessary resources for implementation (10). RTAG also recommended introduction of rubella-containing vaccine into the national infant immunization schedule by 2020. Introduction of combined measles-rubella vaccine would provide an opportunity to build population measles immunity to achieve measles and rubella elimination through a measles-rubella vaccine SIA targeting children aged <15 years.

The findings in this report are subject to at least three limitations. First, administrative coverage might overestimate vaccination coverage through erroneous inclusion of SIA doses or doses administered to children outside of target age groups, inaccurate estimates of the target population size, and inaccurate reports of the number of doses delivered. Second, surveillance data likely underestimate measles incidence because not all patients seek care and not all measles patients who seek care are reported. Finally, efforts to strengthen surveillance over time likely led to reporting bias through increased reporting efficiency annually.

To advance progress toward measles elimination in Pakistan, there is a need to raise the visibility of measles elimination efforts, including the benefits of achieving measles elimination. Without jeopardizing the focused efforts to interrupt poliovirus transmission, transitioning the substantial polio infrastructure and resources should be carefully managed to support measles elimination and broader EMR vaccination goals.