[Back]

M. Chivu-Economescu, C. Bleotu, C. Grancea, D. Chiriac, A. Botezatu, I. Iancu, I. Pitica, L. Necula, A. Neagu, L. Matei, D. Dragu, C. Sultana, E. Radu, A. Nastasie, O. Voicu, M. Ataman, S. Nedeianu, C. Mambet, C. Diaconu, S. Ruta:
"Kinetics and persistence of cellular and humoral immune responses to SARS-CoV-2 vaccine in healthcare workers with or without prior COVID-19";
Journal of Cellular and Molecular Medicine, 26 (2022), 4; 1293 - 1305.

SARS-CoV-2 vaccines are highly efficient against severe forms of the disease, hospi talization and death. Nevertheless, insufficient protection against several circulating viral variants might suggest waning immunity and the need for an additional vaccine dose. We conducted a longitudinal study on the kinetics and persistence of immune responses in healthcare workers vaccinated with two doses of BNT162b2 mRNA vac cine with or without prior SARS-CoV-2 infection. No new infections were diagnosed during follow-up. At 6 months, post-vaccination or post-infection, despite a down ward trend in the level of anti-S IgG antibodies, the neutralizing activity does not decrease significantly, remaining higher than 75% (85.14% for subjects with natural infection, 88.82% for vaccinated after prior infection and 78.37% for vaccinated only).
In a live-virus neutralization assay, the highest neutralization titres were present at baseline and at 6 months follow-up in persons vaccinated after prior infection. Anti-S IgA levels showed a significant descending trend in vaccinated subjects (p < 0.05) after 14 weeks. Cellular immune responses are present even in vaccinated partici pants with declining antibody levels (index ratio 1.1-3) or low neutralizing activity (30%-40%) at 6 months, although with lower T-cell stimulation index (p = 0.046) and IFN-γ secretion (p = 0.0007) compared to those with preserved humoral responses.

antibody levels, IFN-γ, immune response post-infection, immune response post-vaccination, mRNA vaccine, neutralizing antibodies, SARS-CoV-2 infection, spike-specific CD4+ T cell, spike-specific CD8+ T cell

http://dx.doi.org/10.1111/jcmm.17186