Assessment of CD4+, CD8+ T cell and Th1 Cytokine Levels in Healthcare Workers Vaccinated against COVID-19 after the COVAX Initiative in Côte d’Ivoire

Abstract

The COVID-19 pandemic had urgently required the availability of effective vaccines to stop its spread. Despite reports of the effectiveness of these vaccines, SARS-CoV-2 continued to be transmitted. This raised concerns about the immune response to SARS-CoV-2. Two years after the COVAX initiative in our country, we conducted a study to assess the cellular response induced by vaccination among health workers in Abidjan. This was a cross- sectional study that included 350 health workers. It focused on age, sex, workstation, body mass index, history relating to COVID-19, existence of comorbidity, occupational stress, CD4+ T cell levels and CD8+ and the concentrations of the cytokines IFN-γ, TNF-α, IL-6 and IL-2. CD4+ and CD8+ T cell levels and cytokine titers were determined using the BD FACS CANTO II cytometer. Processing was performed using BD FACSCanto software and the CBA protocol. The population average was 40.65 years. CD8+ T-cell levels were significantly correlated with IFN-γ, TNF-α and IL-2 cytokine concentrations. A history of SARS-CoV-2 infection was significantly associated with CD8+ T cell and Th1 cytokine levels. In conclusion, in healthcare workers, T-cell levels continued to increase in the third trimester after vaccination against COVID-19. Additionally, history of SARS-CoV-2 infection appeared to stimulate the cytotoxic T cell response.