| Autor: |
Méndez, Constanza, Peñaloza, Hernán F., Schultz, Bárbara M., Piña-Iturbe, Alejandro, Ríos, Mariana, Moreno-Tapia, Daniela, Pereira-Sánchez, Patricia, Leighton, Diane, Orellana, Claudia, Covarrubias, Consuelo, Gálvez, Nicolás M. S., Soto, Jorge A., Duarte, Luisa F., Rivera-Pérez, Daniela, Vázquez, Yaneisi, Cabrera, Alex, Bustos, Sergio, Iturriaga, Carolina, Urzua, Marcela, Navarrete, María S., Rojas, Álvaro, Fasce, Rodrigo A., Fernández, Jorge, Mora, Judith, Ramírez, Eugenio, Gaete-Argel, Aracelly, Acevedo, Mónica, Valiente-Echeverría, Fernando, Soto-Rifo, Ricardo, Weiskopf, Daniela, Grifoni, Alba, Sette, Alessandro, Zeng, Gang, Meng, Weining, CoronaVac03CL Study Group, González-Aramundiz, José V., González, Pablo A., Abarca, Katia, Melo-González, Felipe, Bueno, Susan M., Kalergis, Alexis M. |
| Abstract: |
BACKGROUND: The Omicron variant has challenged the control of the COVID-19 pandemic due to its immuno-evasive properties. The administration of a booster dose of a SARS-CoV-2 vaccine showed positive effects in the immunogenicity against SARS-CoV-2, effect that is even enhanced after the administration of a second booster. METHODS: During a phase-3 clinical trial, we evaluated the effect of a second booster of CoronaVac®, an inactivated vaccine administered 6 months after the first booster, in the neutralization of SARS-CoV-2 (n = 87). In parallel, cellular immunity (n = 45) was analyzed in stimulated peripheral mononuclear cells by flow cytometry and ELISPOT. FINDINGS: Although a 2.5-fold increase in neutralization of the ancestral SARS-CoV-2 was observed after the second booster when compared with prior its administration (Geometric mean units p < 0.0001, Geometric mean titer p = 0.0002), a poor neutralization against the Omicron variant was detected. Additionally, the activation of specific CD4+ T lymphocytes remained stable after the second booster and, importantly, equivalent activation of CD4+ T lymphocytes against the Omicron variant and the ancestral SARS-CoV-2 were found. INTERPRETATION: Although the neutralizing response against the Omicron variant after the second booster of CoronaVac® was slightly increased, these levels are far from those observed against the ancestral SARS-CoV-2 and could most likely fail to neutralize the virus. In contrast, a robust CD4+T cell response may confer protection against the Omicron variant. FUNDING: The Ministry of Health, Government of Chile, the Confederation of Production and Commerce, Chile and SINOVAC Biotech.NIHNIAID. The Millennium Institute on Immunology and Immunotherapy. |