Elevated antibody titers in Abdala vaccinees evaluated by Elecsys® anti-SARS-CoV-2 S highly correlate with UMELISA SARS-CoV-2 ANTI RBD, ACE-2 binding inhibition and viral neutralization assays

SARS-CoV-2, a recently emerged coronavirus, is causing high morbidity and mortality worldwide since December 2019, posing an enormous health, social and economic problem. Obtaining effective treatments that can diminish deaths and sequelae and vaccines to slow or prevent viral transmission, and reduce disease severity and/or death are of utmost importance. Abdala is a Cuban vaccine based on the recombinant RBD subunit of the spike protein expressed in Pichia pastoris yeast. It demonstrated high efficacy (92.28 %) in phase III clinical trials for reducing transmission, and more than 90% effectiveness in reducing disease severity and mortality. Antibody titers were evaluated in 42 Abdala vaccinees using the Elecsys® Anti-SARS-CoV-2 S test. Fifteen days after immunization, sera from vaccinees showed high antibody titers (median of 1595 U/mL). The results obtained in this study also demonstrate correlation between the Cuban test UMELISA SARS-CoV-2 ANTI RBD used during the clinical trials and Elecsys® test results.\n\nHighlights \n\n### Competing Interest Statement\n\nThe authors have declared no competing interest.\n\n### Funding Statement\n\nThis study was funded by the BioCubaFarma Enterprise and the Center for Genetic Engineering and Biotechnology in Cuba\n\n### Author Declarations\n\nI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.\n\nYes\n\nThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:\n\nCenter for Genetic Engineering and Biotechnology Institutional Ethical Committee approved the Informed Consent requested to human volunteers for the serum samples used.\n\nI confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.\n\nYes\n\nI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).\n\nYes\n\nI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.\n\nYes\n\nAll data produced in the present work are contained in the manuscript