Immunogenicity and safety of boosting with a recombinant two-component SARS-CoV-2 vaccine: two randomized, parallel-controlled, phase 2 studies.

Publication date: Mar 26, 2024

Recombinant protein vaccines play a crucial role in providing broad immuno-protection against SARS-CoV-2 variants. This study evaluates the safety and immunogenicity of ReCOV as a booster dose in two randomized, observer-blinded, active-controlled Phase 2 clinical trials. In Study-1, adults who had received two or three doses of inactivated COVID-19 vaccine were randomized (1:1:1) to receive 20 μg ReCOV, 40 μg ReCOV, or an inactivated vaccine (COVILO(R)) in the United Arab Emirates. Study-2 involved subjects who received two doses of inactivated COVID-19 vaccine and were randomized (1:1:1) to receive 20 μg ReCOV (pilot batch, ReCOV HA), 20 μg ReCOV (commercial batch, ReCOV TC), or 30 μg BNT162b2 (COMIRNATY(R)) in the Philippines. The primary immunogenicity objectives were to compare geometric mean titer (GMT) and seroconversion rate (SCR) of live-virus neutralizing antibodies against SARS-CoV-2 prototype induced by one booster dose of ReCOV with that of inactivated vaccine and BNT162b2, respectively, at 14 days post-booster. Heterologous booster doses of ReCOV were safe, well-tolerated, and elicited noninferior immunogenic responses to inactivated vaccines and BNT162b2 against both Omicron variants and prototype in previously vaccinated adults. The results demonstrated significant advantages in cross-neutralization activities against multiple SARS-CoV-2 variants, surpassing those observed with inactivated vaccines and BNT162b2. Additionally, good immune persistence was noted. Heterologous boosting with ReCOV proved safe and effective, with promising results in managing the COVID-19 epidemic. The study sheds light on the high potential of ReCOV in providing enhanced protection, supported by strong cross-neutralization activities and immune persistence. Study-1, www. clinicaltrials. gov, identifier is NCT05323435; Study-2, www. clinicaltrials. gov, identifier is NCT05084989.

Concepts Keywords
Expert Heterologous booster
Inactivated Immunogenicity
Nct05323435 Omicron variants
Pilot Safety
Vaccine SARS-CoV-2


Type Source Name
disease VO vaccine
disease VO ReCOV
disease VO dose
disease VO COVID-19 vaccine
disease VO inactivated vaccine
disease VO Comirnaty
disease VO titer
disease MESH seroconversion
disease VO vaccinated
disease VO effective
disease MESH COVID-19

Original Article

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