This trial is Stage 2 of a 2-part adaptive trial. The study aims to investigate the safety of 2 doses of a T-cell priming specific cocktail of Coronaviruses peptides mounted on a gold nanoparticle.

Note: Stage 1 of the 2-part adaptive trial, testing a specifically selected mix of Dengue virus peptides, commenced Aug 2021. This is now in follow up (NCT04935801).

Despite drastic quarantine measures, SARS-CoV-2 continues to propagate and threaten global economies and healthcare systems. There is universal consensus on the need for vaccination to protect against complications, reduce viral shedding and therefore prevent severe manifestation of disease and reduce hospitalisations.

Coronavirus harbours the potential to become a seasonal disease. It is moving towards being a ''new flu'' with potential perennial circulation and continuously evolving Variants of Concern (VOCs), needing diverse vaccines to control it. The Global Vaccine Alliance, GAVI, has specifically advocated for vaccine diversity as a means to ensure equality and access as well as a means of maximising scalability.

Nanoparticle antigen delivery systems have been developed to enrich specific targeting of immune receptors. These carrier systems are designed to facilitate antigen uptake and processing by antigen presenting cells (APCs), as well as to control antigen release and protect them from premature proteolytic degradation. This more targeted response also allows to reduce the effective antigen dose (to nanomoles) and mimic a replicating infection with zero risk of developing the infectious disease.

The hypotheses are listed below:

1. The scale of the COVID-19 pandemic requires multiple vaccine candidates to ensure democratic and rapid access to protection by:

   • Providing a range of vaccine choices tailored to variations in immunological profiles across demographics as well as suited to environments with various levels of resources (cold chain etc).
   • Distributing and parallelizing manufacture, to speed up scale, avoid reagent stock limitations and dilute monopolies.

2. The ability for SARS-CoV-2 to mutate, requires multiple vaccine candidates to ensure robust and sustainable protection. Vaccines with a range of epitopes and immune targets provide immunological diversity and reduce vulnerability to mutant escape.

3. Nanotechnology fulfils the needs of a COVID vaccine by being a rapidly scalable and modular platform.

4. Humoral immunity may be transient and insufficient against emerging variants of SARS-CoV-2.

5. Cellular immunity against SARS-CoV-2 is lasting and associated with recovery in COVID-19.

The proposed vaccine of this trial specifically seeks to diversify the immunological target response by carefully curating an MHC-I binding antigen cocktail from the SARS viruses ligandome and loading it onto a robust nanoparticle for controlled release and coupled T-cell immunostimulation. It also specifically seeks to avoid generating a humoral response, which has the potential to be transient and even detrimental in certain cases.

For this second stage of the trial, the objectives are are follows:

Primary:

To evaluate the safety and reactogenicity of two intradermal injections of two different doses of the investigational COVID peptide T-cell inducing vaccine (PepGNP-Covid19) administered to healthy volunteers in Switzerland as a:

1. candidate vaccine for the prevention of COVID-19
2. proof-of-concept for a rapidly scalable modular peptide vaccine platform.

Secondary:

1. To assess the evidence of a CD8 T-cell mediated immune response as a surrogate of protection against severe COVID-19 disease using a novel peptide set-point vaccine in healthy adults.
2. To assess the presence of an antibody mediated response.

For naNO-COVID, a total of 26 eligible participants will be randomised into the following groups:

Group 1 (n=13) 10 low dose (LD) PepGNP-Covid19 (2.5nmol peptide +12.8ug) + 3 Comparator.

Group 2 (n=13) 10 high dose (HD) PepGNP-Covid19 (7.5nmol + 38.3ug) + 3 Comparator.

Thus, 20/26 vaccine and 6/26 Comparator controls. Allocations of vaccine vs bpC for each group are double-blinded. Each arm will be staggered into a ''Pioneer'' group (3/13 participants) followed a week later after a safety review by the remaining 10/13 ''Followers''.

This is the second stage of a 2-stage study investigating the safety of 2 vaccines from a T-cell priming vaccine platform for emerging diseases. (stage 1 = naNO-Dengue, stage 2 = naNO-COVID).

Inclusion Criteria:

• Aged 18 to 45 years on the day of inclusion
• Participant signed informed consent
• Residing in Switzerland

Exclusion Criteria:

• Participant is pregnant, lactating or of childbearing potential
• Participation in the 4 weeks preceding the first trial vaccination or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device or medical procedure.
• Receipt of any vaccine (including vaccine against COVID) in the 4 weeks preceding the first trial vaccination (excluding influenza vaccination which may be received 2 weeks prior to the first vaccination), or planned receipt of any vaccine in the 4 weeks following each trial vaccination.
• Positive SARS-CoV2 test in the 4 weeks preceding the first trial vaccination.
• Receipt of immunoglobins, blood or blood-derived products in the past 3 months.
• Known, or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy.
• Self-reported or documented seropositivity for human immunodeficiency virus (HIV), hepatitis B natural infection, (HBcAb positive serology) or hepatitis C.
• Known systemic hypersensitivity to any of the vaccine components (e.g gold,) or history of a life-threatening reaction to vaccines.
• Current alcohol abuse or drug addiction (reported or suspected)
• Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion.
• Thrombocytopenia or any coagulation disorder
• Identified as an Investigator or employee of the Investigator or study centre with direct involvement in the proposed study, or identified as an immediate family member (i.e parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study (i.e in the employment of the Tropivac Clinic or DFRI unit at Unisante).
• Refusal to be informed in the event that relevant results concerning the participant's health are revealed.

The following events constitute contraindications to the administration of the investigational product on the day of planned vaccination: The participant must be followed until resolution of the event as with any medical event and may be considered for vaccination at a later date (maximum 14 days later) or withdrawn at the discretion of the Investigator. Delays due to these events do not constitute a protocol deviation.

• Temperature of >37.5°C at the time of vaccination
• Acute disease at the time of vaccination (defined as the presence of a moderate or severe illness with or without fever according to investigator's judgment. All vaccines can be administered to persons with a minor illness such as diarrhoea, mild upper respiratory infection with or without low-grade febrile illness, i.e. axillary temperature of ≤ 37.5°C).

The Investigators will be involved in writing and /or reviewing drafts of the manuscripts, abstracts, press releases and any other publications arising from the study.

Apart from the obvious flaws to conduct of the study, which may preclude data publication, safety and efficacy data will be published under the supervision and authorisation of the PI and Sponsor.

Publication will include as much individual level data as possible to ensure reproducibility of results without compromising participant privacy.

Within 12 months of study completion

Peer-reviewed publication

• This trial is double-blinded (blinded to investigators and participants)
• Blinding will be maintained for the duration of the study
• All allocations will remain coded to all volunteers and investigators. An independent pharmacy team at CHUV will label the vaccine and comparator doses with coded participant numbers but will not have access to the identifier list linking the code to the participant identity. All vaccine and comparator doses will be prepared and labelled away from investigators and stored in identical conditions.
• The appearance of the comparators and doses will be identical. The solutions of both are indistinguishable within the dosage group and thus no shielding of the solution colour is needed.