RESUMEN
We evaluated response to a single dose of the FINLAY-FR-1A recombinant dimeric-RBD base vaccine during a phase I clinical trial with 30 COVID-19 convalescents, to test its capacity for boosting natural immunity. This short report shows: a) an excellent safety profile one month after vaccination for all participants, similar to that previously found during vaccination of naive individuals; b) a single dose of vaccine induces a >20 fold increase in antibody response one week after vaccination and remarkably 4-fold higher virus neutralization compared to the median obtained for Cuban convalescent serum panel. These preliminary results prompt initiation of a phase II trial in order to establish a general vaccination protocol for convalescents.
RESUMEN
Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to use neutralizing antibodies to block viral sites binding to the hosts cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of the immunization and correlates well with viral neutralization. Here we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid induce a potent immune response in laboratory animals. Some advantages of the immunization with the viral antigen coupled to tetanus toxoid have become evident such as predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. This paper demonstrates that subunit conjugate vaccines can be an alternative for COVID-19, paving the way for other viral conjugate vaccines based on the use of small viral proteins involved in the infection process.