Abstract:
Cellular and humoral responses, as well as virus replication kinetics, may affect the severity of
COVID-19. This study examined systemic and mucosal immune responses as well as viral load in
unvaccinated SARS-CoV-2 patients. Forty-eight COVID-19-positive, grouped into asymptomatic,
moderate and severe disease, and 48 COVID-19-negative individuals at Moi Teaching and Referral
Hospital in Kenya were included. Severe patients showed higher viral loads and systemic anti
spike IgG compared to moderate and asymptomatic individuals. Asymptomatic individuals had
higher mucosal anti-spike IgG and receptor binding domain (RBD) levels compared to severe
patients. Systemic IFN-α mRNA transcript was expressed at higher levels in asymptomatic
individuals compared to patients with severe COVID-19 and healthy individuals. Severe patients
had significantly lower expression of IFN-γ mRNA transcript levels in both blood and mucosa, as
well as significantly lower systemic IFI-16 mRNA transcript levels. These results suggest that
mucosal anti-spike and RBD IgG may offer protection, while systemic antibodies indicate disease
progression. Suppressed interferon responses, both mucosal and systemic, were linked to severe
disease. To conclude, viral load, IFN, anti-viral, and systemic IgGs could help predict COVID-19
outcomes and aid in developing personalized treatment strategies.
