Anti-inflammatory SARS-CoV-2 T cell immunity in asymptomatic seronegative Kenyan adults

Antibodies are used to estimate prevalence of past infection. However, T cell responses against SARS-CoV-2 may more accurately define prevalence because SARS-CoV-2-specific antibodies wane. In November-December 2021, we studied serological and cellular immune responses in residents of rural Kenya who had not experienced any respiratory symptom nor had contact with COVID-19 cases. Among participants we detected anti-spike antibodies in 41.0% and T cell responses against ≥2 SARS-CoV-2 proteins in 82.5%, which implies that serosurveys underestimate SARS-CoV-2 prevalence in settings where asymptomatic infections prevail. Distinct from cellular immunity in European and Asian COVID-19 convalescents, strong T cell immunogenicity was observed against viral accessory proteins in these asymptomatic Africans, as well as a higher IL-10/IFN-γ ratio cytokine profile, suggesting that environmental or genetic factors modulate pro-inflammatory responses. Funding U.S. Centers for Disease Control and Prevention, Division of Global Health Protection. Singapore Ministry of Health’s National Medical Research Council under its COVID-19 Research Fund (COVID19RF3-0060, COVID19RF-001 and COVID19RF-008) and the Singapore Ministry of Health’s National Medical Research Council MOH-000019 (MOH-StaR17Nov-0001).