A prospective study of the protective effect of SARS-CoV-2-specific antibodies and T cells in Moscow residents

Molodtsov, I.; Kegeles, E.; Mitin, A.; Mityaeva, O.; Musatova, O.; Panova, A.; Pashenkov, M.; Peshkova, I.; Almaqdad, A.; Asaad, W.; Budikhina, A.; Deryabin, A.; Dolzhikova, I.; Filimonova, I.; Gracheva, A.; Ivanova, O.; Kizilova, A.; Komogorova, V.; Komova, A.; Kompantseva, N.; Lagutkin, D.; Lomakin, Y.; Maleeva, A.; Maryukhnich, E.; Mohammad, A.; Murugin, V.; Murugina, N.; Navoikova, A.; Nikonova, M.; Ovchinnikova, L.; Pinegina, N.; Potashnikova, D.; Romanova, E.; Saidova, A.; Sakr, N.; Samoilova, A.; Serdyuk, Y.; Shakirova, N.; Sharova, N.; Sheetikov, S.; Shemetova, A.; Shevkova, L.; Shpekt,

Background: Coronavirus disease COVID-19 has spread worldwide extremely rapidly. Although many individuals have been infected and have cleared the virus, developing virus-specific antibodies and effector/memory T cells, an important question still to be answered is what levels of T cell and antibody responses are sufficient to protect from the infection. Methods: In 5,340 Moscow residents, we evaluated the anti-SARS-CoV-2 IgM/IgG titers and the frequencies of the T cells specific to the nucleocapsid, membrane, and spike proteins of SARS-CoV-2, using IFNy; ELISpot, and we also evaluated the fractions of virus-specific CD4+ and CD8+ T cells using intracellular staining of IFNy; and IL2 followed by flow cytometry. Furthermore, we analyzed the post-inclusion COVID-19 rates as a function of the assessed antibody and T cell responses using the Kaplan-Meyer estimator method. Results: We showed that T cell and antibody responses are closely interconnected and commonly are induced concurrently. Individuals positive for both antibody and T cell immunities demonstrated the highest levels of protectivity against the SARS-CoV-2 infection, indistinguishably from individuals with antibody response only. Meanwhile, individuals with T cell response only demonstrated slightly higher protectivity than individuals without both types of immunity, as measured from N-protein-specific or CD4+IL2+ T cells. However, these individuals were characterized by higher IgG titers than individuals without any immunity, although the titers were below the seropositivity cut-off. Conclusions: The results of the study indicated the advantage of serology testing over the analysis of T cell responses for the prediction of SARS-CoV-2 infection rates on a populational level.