Prevalence and functional profile of SARS-CoV-2 T cells in asymptomatic Kenyan adults.

BackgroundSARS-CoV-2 infection in Africa has been characterized by a less severe disease profile than what has been observed elsewhere, but the profile of SARS-CoV-2-specific adaptive immunity in these mainly asymptomatic patients has not, to our knowledge, been analyzed.MethodsWe collected blood samples from residents of rural Kenya (n = 80), who had not experienced any respiratory symptoms or had contact with individuals with COVID-19 and had not received COVID-19 vaccines. We analyzed spike-specific antibodies and T cells specific for SARS-CoV-2 structural (membrane, nucleocapsid, and spike) and accessory (ORF3a, ORF7, ORF8) proteins. Pre-pandemic blood samples collected in Nairobi (n = 13) and blood samples from mild-to-moderately symptomatic COVID-19 convalescent patients (n = 36) living in the urban environment of Singapore were also studied.ResultsAmong asymptomatic Africans, we detected anti-spike antibodies in 41.0% of the samples and T cell responses against 2 or more SARS-CoV-2 proteins in 82.5% of samples examined. Such a pattern was absent in the pre-pandemic samples. Furthermore, distinct from cellular immunity in European and Asian COVID-19 convalescents, we observed strong T cell immunogenicity against viral accessory proteins (ORF3a, ORF8) but not structural proteins, as well as a higher IL-10/IFN-γ cytokine ratio profile.ConclusionsThe high incidence of T cell responses against different SARS-CoV-2 proteins in seronegative participants suggests that serosurveys underestimate SARS-CoV-2 prevalence in settings where asymptomatic infections prevail. The functional and antigen-specific profile of SARS-CoV-2-specific T cells in African individuals suggests that environmental factors can play a role in the development of protective antiviral immunity.FundingUS Centers for Disease Control and Prevention, Division of Global Health Protection; the Singapore Ministry of Health's National Medical Research Council (COVID19RF3-0060, COVID19RF-001, COVID19RF-008, MOH-StaR17Nov-0001).

Medicinal plants used by Luo mothers and children in Bondo district, Kenya.

In a follow-up to studies of school-children's medical knowledge among the rural Luo of western Kenya, seven mothers were asked for their knowledge of plant medicine, and the 91 plant remedies mentioned by them were collected, 74 of these remedies were identified as 69 different species (in 13 cases, the material did not allow identification of the species, in two cases, only the family could be identified, and in two, not even this was possible). The results of this survey and some comments on Luo illness concepts are presented below and briefly discussed in relation to the earlier work on school-children and to another survey of Luo plant medicine in the same district. The article concludes that the consensual core of Luo plant medicine is known by ordinary mothers and their children as well as by recognised healers. It is a shared resource, that is used by women, mainly in the care for their children, and it is not an expert domain of knowledge, as is often, in studies of herbal or 'traditional' medicine are studied. The medicinal plants, upon which many mothers as well as healers agree should be examined further pharmacologically in order to assess their efficacy against the common infectious and parasitic diseases found in this area of western Kenya.