A Phase II Study Integrating a Single-Blind Safety Phase with a Double-Blind, Placebo-Controlled Randomized Phase, Assessing Single-Dose Intramuscular or Intranasal Administration to Evaluate the Safety and Immunogenicity of the Recombinant Vaccine Against COVID-19 (AVX/COVID-12 “Patria”) Based on an Active Newcastle Disease Viral Vector as a Heterologous Booster in Subjects with Evidence of Previous Immunity to SARS-CoV-2

Background The global inequity in coronavirus disease 2019 (COVID-19) vaccine distribution, primarily affecting low- and middle-income countries (LMICs), highlights the urgent need for innovative and cost-effective vaccine technologies to address availability disparities. This is crucial for achieving and sustaining widespread immunity and protecting vulnerable populations during future booster campaigns. Methods To address this need, we conducted a phase II clinical trial evaluating the safety and immunogenicity of the AVX/COVID-12 “Patria” vaccine as a booster dose. The vaccine was administered through both intramuscular (IM) and intranasal (IN) routes to participants who had previously received severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines based on adenoviral technology, inactivated virus, or mRNA technology. The inclusion criterion involved individuals with initial anti-spike IgG titers below 1,200 U/mL, allowing observation of the booster effect induced by vaccination. Results Immunization with AVX/COVID-12 resulted in a significant (>2.5 times) increase in neutralizing antibodies against the original Wuhan strain and variants of concern (VOCs) such as Alpha, Beta, Delta, and Omicron (BA.2 and BA.5). This immune response was accompanied by cellular interferon-gamma (IFN-γ) production, indicating a robust and multifaceted reaction. Conclusions The administration of AVX/COVID-12 as a booster dose, whether through IM or IN routes, was safe and well-tolerated. The vaccine extended immune responses not only against the original Wuhan-1 strain but also against various VOCs. Its ability to enhance preexisting immune responses suggests a potential contribution to expanding and sustaining herd immunity within the population. ### Competing Interest Statement The vaccine candidate administered in this study was developed by faculty members at the Icahn School of Medicine at Mount Sinai including P.P., F.K., and A.G.-S. Mount Sinai is seeking to commercialize this vaccine; therefore, the institution and its faculty inventors could benefit financially. The Icahn School of Medicine at Mount Sinai has filed patent applications relating to SARS-849 CoV-2 serological assays (USA Provisional Application Numbers: 62/994,252, 63/018,457, 63/020,503, and 63/024,436) and NDV-based SARS-CoV-2 vaccines (USA Provisional Application Number: 63/251,020) which list F.K. as co-inventor. A.G.-S. and P.P. are co-inventors in the NDV-based SARS-CoV-2 vaccine patent application. Patent applications were submitted by the Icahn School of Medicine at Mount Sinai. Mount Sinai has spun out a company, Kantaro, to market serological tests for SARS-CoV-2 and another company, CastleVax, to commercialize SARS-CoV-2 vaccines. F.K., P.P., and A.G.-S. serve on the scientific advisory board of CastleVax and are listed as co-founders of the company. F.K. has consulted for Merck, Seqirus, Curevac, and Pfizer, and is currently consulting for Gritstone, Third Rock Ventures, GSK, and Avimex. The F.K. laboratory has been collaborating with Pfizer on animal models of SARS-CoV-2. C.L.-M. has consulted for AstraZeneca. The A.G.-S. laboratory has received research support from GSK, Pfizer, Senhwa Biosciences, Kenall Manufacturing, Blade Therapeutics, Avimex, Johnson & Johnson, Dynavax, 7Hills Pharma, Pharmamar, ImmunityBio, Accurius, Nanocomposix, Hexamer, N-fold LLC, Model Medicines, Atea Pharma, Applied Biological Laboratories, and Merck. A.G.-S. has consulting agreements for the following companies involving cash and/or stock: Amovir, Vivaldi Biosciences, Contrafect, 7Hills Pharma, Avimex, Pagoda, Accurius, Esperovax, Farmak, Applied Biological Laboratories, Pharmamar, CureLab Oncology, CureLab Veterinary, Synairgen, Paratus, Pfizer, and Prosetta. A.G.-S. has been an invited speaker in meeting events organized by Seqirus, Janssen, Abbott, and AstraZeneca. PP has a consulting agreement with Avimex. Members of Avimex developed the live vaccine used in this study. Avimex filed patent applications with Mount Sinai and CONAHCYT. M.T., D.S.-M., C.L.-M., H.E.C.-C., F.C.-P., G.P.D.L., and B.L.-D. are named as inventors on at least one of those patent applications. The clinical study was entirely performed in Mexico, and Mount Sinai had no role in it. The rest of the participants are employees of their corresponding institutions and declare no competing interests. ### Clinical Trial NCT05205746 ### Funding Statement The funding for the clinical study was provided by the National Council for Humanities, Science and Technology (CONAHCYT, Mexico), except for all the production and vaccine product supply, which was funded solely by Laboratorio Avi-Mex, S. A. de C. V. (Avimex). CONAHCYT did not participate in the trial design but did evaluate it and approved the project through their National Committee for Science, Technology and Innovation in Public Health. Funding was managed by Avimex and used to pay for all laboratory tests, clinical sites, and clinical professionals. CONAHCYT also facilitated the identification, purchase, and importation of certain supplies and the communication with other entities of the Federal Mexican Government to facilitate the study. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approval for the study was obtained from the Federal Commission for the Protection against Sanitary Risks (COFEPRIS) in Mexico, under the assigned number RNEC2021-AVXSARSCoV2VAC002. As a prerequisite, local ethics clearance was secured from the institutional ethics committees at each participating research site. Research Site 1: Unidad de Investigacion Medica en Epidemiologia Clinica, UMAE Hospital de Especialidades, Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico. Ethics Committee: IMSS Scientific Research National Committee. Approval Number: R-CNIC-R-2021-785-121. Research Site 2: CAIMED Investigacion en Salud, S.A. de C.V., Mexico City. Ethics Committee: Biomedical Research Ethics Committee for Drug Development. Approval Number: 3937.7mYWSpu. Research Site 3: Oaxaca Site Management Organization (OSMO) S.C., Oaxaca, Mexico. Ethics Committee: OSMO Research Ethics. Approval Number: CEI-OSMO: 616/2022. The research fully adhered to Mexican regulations and the principles outlined in the Declaration of Helsinki and Good Clinical Practice. I 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. Yes I 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). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The protocol was registered in the National Registry of Clinical Studies under number RNEC2021-AVXSARSCoV2VAC002 and published under [NCT05205746][1]. Individual de-identified participant data will not be shared beyond the limits permitted by the informed consent and Mexican law. Specifically, this includes the sharing of the study protocol, statistical analysis plan, informed consent form, and approved clinical study report. Additionally, other de-identified data allowed under the informed consent and Mexican law may be shared. The data will be made available immediately upon publication and for 12 months thereafter. Access to the data will be granted solely to investigators with methodologically sound proposals, subject to authorization by an independent review committee and the ethics committees involved in approving the protocol. If required by law, authorization from the Federal Commission for the Protection against Sanitary Risks (COFEPRIS) in Mexico will also be obtained. Any use of the data must strictly adhere to the authorized purposes outlined during the approval process. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05205746&atom=%2Fmedrxiv%2Fearly%2F2024%2F02%2F13%2F2024.02.11.24302594.atom