Rubella epidemiology in Lesotho after vaccine introduction: a five-year review, 2018–2022

Abstract

BackgroundThe rubella virus is a major contributor to birth defects globally and is preventable by vaccination. In 2020, the world was supposed to be free of both rubella and Congenital Rubella Syndrome (CRS) however this goal has yet to be realized with only 93 out of 194 WHO member states confirmed rubella-free in 2020.MethodsA retrospective measles and rubella case-based surveillance data record review was conducted from 2018 to 2022 to document rubella epidemiology after the introduction of rubella vaccination in Lesotho and progress toward elimination. All samples submitted for surveillance purposes and tested for rubella were considered but only filtered according to inclusion and exclusion criteria. Descriptive statistics were used to analyse the data.ResultsOf the 1041 samples that were tested for rubella between 2018 and 2022, 10 (1%) were confirmed measles positive and were excluded from further analysis. The median age of the respondents was 6.0 (IQR 4.0–8.0.) years. About 643 (62.4%) of respondents were in the age category of 5 - <13 years. Rubella prevalence was 1% (95% CI; 0.5 -1.8%). The non-measles, non-rubella rash illness rate of 2 per 100 000 population was obtained at the national level each year of the study period but by only 2 of the country’s 10 districts in 2021.ConclusionsThe study showed low rubella prevalence. Rubella infection was predominant in those aged 5 - < 13 years. Failure to meet surveillance targets at certain time points during the study period may have led to an underestimation of rubella cases. There is a need to improve the quality of measles and rubella surveillance in Lesotho. Supplementary immunization activities would also be useful in closing immunity gaps, limiting outbreaks, and advancing rubella and CRS elimination in Lesotho.