High SARS-CoV-2 seroprevalence among street adolescents in Lomé, Togo, 2021.

Background: There is almost no data on the circulation of SARS-CoV-2 among street adolescents. We conducted a study to document the immunization status of street adolescents in Togo against different variants of SARS-CoV-2.

Methods: A cross-sectional study was carried out in 2021 in Lomé, the city with the highest number of COVID 19 cases in Togo (60%). Adolescents aged 13- and 19 years old living on the street were eligible for inclusion. A standardized questionnaire was administered face-to-face to adolescents. A sample of blood was taken and aliquots of plasma were transported to the virology laboratory of the Hôpital Bichat-Claude Bernard (Paris, France). SARS-CoV-2 anti-S and anti-N IgG were measured using chemiluminescent microparticle immunoassay. A quantitative miniaturized and parallel-arranged ELISA assay was used to detect IgG antibodies specifically directed against the different SARS-CoV-2 Variants of Concern (VOC).

Results: A total of 299 street adolescents (5.2% female), median age 15 years, interquartile range (14-17 years), were included in this study. The prevalence of SARS-CoV-2 infection was 63.5% (95%CI: 57.8-69.0). Specific-IgG against the ancestral Wuhan strain was developed by 92.0% of subjects. The proportion of patients being immunized against each VOC was 86.8%, 51.1%, 56.3%, 60.0, and 30.5% for the Alpha, Beta, Gamma, Delta, and Omicron VOCs, respectively.

Conclusion: This study showed a very high prevalence with approximately 2/3 of Togolese street adolescents having antibodies to SARS-CoV-2 due to a previous infection. These results confirm an under-reporting of COVID-19 cases in Togo, questioning the hypothesis of low virus circulation in Togo and even in Africa.