Booster vaccination with a recombinant subunit vaccine against SARS-CoV-2 increases antigen specific mucosal antibodies

FEDERICO PÁEZ CÓRDOBA; CLARA G. FASCETTO CASSERO; CORIA, LORENA; GONZALO PEREZ MARC; CEBALLOS, ANA; RODRIGUEZ, JUAN MANUEL; LOMBARDO, MÓNICA; BRUNO LAURA; DEMARÍA, AGOSTINA; PRADO, LINEIA; CASTRO, CELESTE PUEBLAS; DE OCA, FEDERICO MONTES; VEGA, JULIO C.; FLO, JUAN M.; PABLO BONVEHI; CASSARA JORGE; CASSATARO JULIANA; KARINA PASQUEVICH

Universidad Católica Argentina, Buenos Aires, Argentina

Congreso; 14th Latin American and Caribbean Congress of Immunology; 2024

: A Phase II/III clinical trial for a SARS-CoV-2 recombinant booster vaccine (ARVAC CG) was conducted in Argentina with three different RBD versions: ARVACGamma, ARVACOmicron BA.4/5 and ARVACBivalent. The clinical trial was randomized, double-blind, crossover, placebo-controlled and multicenter including adult volunteers previously vaccinated against SARS-CoV-2 with ≤3 booster doses. An exploratory endpoint of the clinical trial was the study of the systemic and mucosal antibody response induced 14 days after vaccination in a subset of 200 volunteers. In Phase II 30 volunteers received Placebo treatment and 50 volunteers received ARVACGamma. Whereas in Phase III, there were 30 volunteers for each brunch assayed (Placebo, ARVACGamma, ARVACOmicron BA.4/5 and ARVACBivalent). Systemic IgG response was assessed in plasma samples by commercial ELISA kit (COVIDAR) for the detection of anti-Spike antibodies. Mucosal IgA response was assessed in saliva samples by commercial ELISA kit (EUROINMUNE) for the detection of anti-S1 antibodies. Response of antigen-specific antibodies in plasma and saliva samples was analyzed considering parameters such as: previous SARS-CoV-2 infection status (anti-N IgG levels in plasma), primary vaccination platform, presence or absence of booster, and sex of the volunteers. In Phase II, there were significant increases in both IgG and IgA levels at day 14 in volunteers who were vaccinated with ARVACGamma independently of the parameters previously mentioned. Placebo volunteers did not show statistical difference. In Phase III, IgG levels increased significantly with all three ARVAC versions regardless of the parameters assessed. IgA levels increased significantly with all three ARVAC versions when all Phase III volunteers were not subdivided according to the parameters previously mentioned. These results showed that a booster dose with ARVAC increases anti-Spike IgG levels in plasma and anti-S1 IgA levels in saliva at 14 days vaccination.