ABSTRACT
Population-based serological testing is important to understand the epidemiology and estimate the true cumulative incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to inform public health interventions. This study reports findings of a national household population SARS-CoV-2 serosurvey in people 12 years and older in South Africa. This cross-sectional multi-stage random stratified cluster survey undertaken from November 2020 to June 2021 collected sociodemographic data, medical history, behavioural data, and blood samples from consenting participants. The samples were tested for SARS-CoV-2 antibodies using the Roche ElecsysAnti-SARS-CoV-2 chemiluminescence immunoassay (CLIA) Total Antibody Test. The survey data were weighted by age, race, sex, and province with final individual weights benchmarked against the 2020 mid-year population estimates and accounted for clustering. Descriptive statistics summarize the characteristics of participants and seroprevalence. Logistic regression analyses were used to identify factors associated with seropositivity. From 13290 survey participants (median age 33 years, interquartile range (IQR) 23-46 years), SARS-CoV-2 seroprevalence was 37.8% [95% Confidence Interval (CI) 35.4-40.4] and varied substantially across the country's nine provinces, and by sex, age and locality type. In the final adjusted model, the odds of seropositivity were higher in women than in men [aOR = 1.3 (95% CI: 1.0-1.6), p = 0.027], and those living with HIV (self-report) [aOR = 1.6 (95% CI: 1.0-2.4), p = 0.031]. The odds were lower among those 50 years and older compared to adolescents 12-19 years old [aOR = 0.6 (95% CI: 0.5-0.8), p<0.001] and in those who did not attend events or gatherings [aOR = 0.7 (95% CI: 0.6-1.0), p = 0.020]. The findings help us understand the epidemiology of SARS-CoV-2 within different regions in a low-middle-income country. The survey highlights the higher risk of infection in women in South Africa likely driven by their home and workplace roles and also highlighted a need to actively target and include younger people in the COVID-19 response.
ABSTRACT
South Africa has yet to introduce a rubella-containing vaccine (RCV) into its Expanded Programme on Immunisation (EPI). Here we evaluated the incidence of laboratory-confirmed rubella and congenital rubella syndrome (CRS) cases over the years 2015 to 2019, to document the epidemiology of rubella and CRS within South Africa prior to a RCV introduction. This retrospective study evaluated the number of laboratory-confirmed rubella cases reported through the national febrile rash surveillance system. A positive test for rubella immunoglobulin M (IgM) antibodies was considered a confirmed rubella case. For CRS cases, we reported laboratory-confirmed CRS cases collected from 28 sentinel-sites from all nine provinces of South Africa. From 2015-2019, 19 773 serum samples were tested for rubella IgM antibodies, 6 643 (33.6%) were confirmed rubella cases. Rubella was seasonal, with peaks in spring (September to November). Case numbers were similar between males (n = 3 239; 50.1%) and females (n = 3 232; 49.9%). The highest burden of cases occurred in 2017 (n = 2 526; 38%). The median age was 5 years (IQR: 3-7 years). Importantly, of females with rubella, 5.0% (161 of 3 232) of the cases were among women of reproductive age (15-44 years). A total of 62 CRS cases were reported, the mortality rate was 12.9% (n = 8), and the most common birth defect was congenital heart disease. In conclusion, rubella is endemic in South Africa. Children below the age of 10 years were the most affected, however, rubella was also reported among women of reproductive age. The baseline data represented here provides insight into the burden of rubella and CRS in South Africa prior to the introduction of a RCV, and can enable planning of RCV introduction into the South African EPI.
