Lesotho is a lower-middle-income, mountainous, landlocked country with an estimated population of 2,379,237 in 2026 and an annual birth cohort of about 42,540. Immunization is a core national health strategy delivered predominantly through facility-based services with outreach and mobile strategies for remote areas. The Expanded Program on Immunization includes the first dose of measles-containing vaccine (MCV1) at 9 months and the second dose (MCV2) at 18 months; MCV2 was introduced in 2001. Rubella-containing vaccine (RCV) was introduced in 2017, replacing monovalent measles vaccine with the combined MR vaccine. Lesotho faces a high HIV burden, which has implications for infant susceptibility to measles due to potentially faster waning of maternal antibodies in HIV-infected mothers.
The WHO African Region’s measles elimination targets require ≥95% coverage with two timely MCV doses, sensitive case-based surveillance (non-measles febrile rash illness rate ≥2/100,000 and ≥80% of districts reporting at least one suspected case with specimen annually), and measles incidence <1 case per million population. This manuscript assesses Lesotho’s performance against those criteria for 2011–2025.
This study used a retrospective review of national immunization and surveillance data from 2011 through 2025. Routine coverage was assessed using WHO/UNICEF Estimates of National Immunization Coverage (WUENIC) for MCV1 and MCV2. Supplemental immunization activity (SIA) performance was reviewed using administrative coverage and post-campaign coverage survey (PCCS) estimates where available. Measles and rubella case-based surveillance data were extracted from the WHO AFRO database. Surveillance sensitivity was evaluated using the non-measles febrile rash illness (NMFRI) rate and the proportion of districts reporting at least one suspected measles case with a blood specimen. Annual incidence rates for confirmed measles and confirmed rubella were calculated per 1 million population.
Between 2011 and 2016, MCV1 coverage in Lesotho consistently reached at least 90% but did not attain the 95% elimination benchmark. The period under review showed a decline in MCV1 performance in 2022 and 2023 to 84% and 76% respectively, with recovery to 90% reported in 2024. MCV2 coverage reached ≥80% only in 2011 and 2012 and declined thereafter. MCV1–MCV2 dropout rates were 9–10% in 2011–2012 and exceeded 10% in most years from 2013–2024, indicating substantial loss to follow-up between first and second doses.
The country currently delivers additional interventions (DT4 booster and vitamin A) during the second year of life alongside MCV2, but the review highlights the need for a structured second-year-of-life platform and introduction or scaling of other high-priority interventions to improve MCV2 uptake.
Lesotho has conducted nationwide SIAs at intervals of 2–5 years since a major catch-up campaign in 1999–2000. Most SIAs between 2010 and 2025 were follow-up campaigns targeting children aged 9–59 months, while the 2017 catch-up targeted 9–14 year olds concurrent with RCV introduction. Administrative coverage across campaigns varied widely, from 45.1% in 2022 to 91.0% in 2010. PCCS validation was not available for the 2022 campaign; for the other reviewed SIAs, PCCS estimates ranged from 83.7% (2025) to 94.3% (2010).
The 2022 SIA had low administrative coverage and no PCCS, and was reported to have been rushed and inadequately resourced, with inadequate social mobilisation and communication due to concurrent integration with COVID-19 vaccination activities. The long interval to the next SIA (2017–2022) contributed to accumulation of susceptible children and was implicated in the resurgence of measles cases.
Lesotho’s case-based measles-rubella surveillance system has been functional for over two decades. The national NMFRI rate consistently exceeded the WHO minimum target of 2 per 100,000 population across most years, ranging from 2.5 in 2016 to 36.9 in 2023. The proportion of districts reporting at least one suspected measles case with a blood specimen met the ≥80% target in most years, although the target was not met in 2011 and 2021.
Lesotho has not yet established congenital rubella syndrome (CRS) sentinel surveillance nor conducted retrospective record reviews to quantify CRS burden. The country also has no documented measles or rubella virus genotypes recorded in global sequence databases according to the report.
From 2011 to 2015, confirmed measles incidence remained below 1 per 1 million population. During those same early years, many suspected measles cases tested negative for measles but were IgM-positive for rubella, with rubella incidence ranging from 33.4 per million in 2012 to 142.3 per million in 2014. After RCV introduction in 2017 rubella incidence declined significantly to below 1 per million by 2018, but rubella incidence rose again in 2022–2023.
Measles incidence remained below 5 per million in 2016–2019 but increased after the COVID-19 period; reported measles incidence was 7.4 per million in 2023 and 9.7 per million in 2025. The review attributes increases to immunity gaps resulting from long intervals between SIAs and suboptimal SIA performance, compounded by cross-border transmission risk from neighboring countries experiencing outbreaks.
Lesotho has made measurable progress toward measles and rubella elimination: sustained high MCV1 performance for many years, a functioning case-based surveillance system that generally meets sensitivity targets, and marked reduction in rubella incidence following RCV introduction in 2017. However, the country has not met the critical elimination criteria of ≥95% coverage with two timely MCV doses and sustained measles incidence <1 per million for the full review period.
Key programmatic gaps identified in the data include: persistent low MCV2 uptake and high dropout, periodic poorly implemented SIAs (notably 2022), inaccuracies in population denominators leading to discrepancies between administrative and survey coverage, absence of CRS sentinel surveillance, and lack of documented measles or rubella virus genotypes. These gaps permit accumulation of susceptible cohorts and increase outbreak risk, particularly in the context of cross-border transmission.
Based on the reported findings, the paper recommends strengthening routine immunization in the second year of life to improve MCV2 coverage, implementing structured approaches to the 18-month well-child visit to reduce dropouts, and adding high-priority interventions to the second-year platform. SIAs require improved planning, adequate resources, and robust social mobilisation and communication to reach eligible children and avoid missed cohorts. Addressing denominator inaccuracies—through census or scientifically valid estimation methods—is essential for credible coverage monitoring.
The country should establish CRS sentinel surveillance and conduct retrospective reviews to define CRS burden, and systematically document measles and rubella virus genotypes in global databases to support outbreak investigation and elimination verification. Regional coordination with neighboring countries is also advised to reduce re-introduction risks.
The source article notes these conclusions and recommendations; specific operational plans, timelines, and additional country actions beyond those reported were not described in the source.