The severity of COVID-19 is a result of the complex interplay between various branches of the immune system. However, our understanding of the role of neutralizing antibodies and the activation of cellular immune response in COVID-19 pathogenesis remains limited. In this study, we investigated neutralizing antibodies in patients with mild, moderate, and severe COVID-19, analyzing their cross-reactivity with the Wuhan and Omicron variants. We also assessed the activation of the immune response by measuring serum cytokines in patients with mild, moderate, and severe COVID-19. Our findings suggest the early activation of neutralizing antibodies in moderate COVID-19 compared to mild cases. We also observed a strong correlation between the cross-reactivity of neutralizing antibodies to the Omicron and Wuhan variants and the severity of the disease. In addition, we found that Th1 lymphocyte activation was present in mild and moderate cases, while inflammasomes and Th17 lymphocytes were activated in severe COVID-19. In conclusion, our data indicate that the early activation of neutralizing antibodies is evident in moderate COVID-19, and there is a strong correlation between the cross-reactivity of neutralizing antibodies and the severity of the disease. Our findings suggest that the Th1 immune response may play a protective role, while inflammasome and Th17 activation may be involved in severe COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic remains a significant public health threat globally with significant socio-economic impacts. People living with human immunodeficiency virus (HIV) (PLWH) have a high risk of severe outcomes of COVID-19 due to immunosuppression. Clinical manifestation of COVID-19 in HIV patients largely remains unclear. We carried out a pilot study to investigate the clinical laboratory data and circulating cytokines in PLWH infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in Tatarstan, Russia. Serum samples were collected from three groups: PLWH with COVID-19 (PLWH/COVID-19), COVID-19-only, and uninfected controls. We found an increased risk of severe COVID-19 in PLWH/COVID-19 patients compared to COVID-19-only. Four fatal cases were in PLWH/COVID-19, while there was no fatality in COVID-19-only. Pro-inflammatory cytokines, such as IL-5, IL-6, IL-9, and IL-15, were elevated in PLWH/COVID-19 compered to COVID-19-only. These preliminary findings highlight the potential for more severe COVID-19 in PLWH/COVID-19 where pro-inflammatory cytokines could play pathogenic role.