Anti-COVID19 VaccinaTion AKS-452 BOOSTER (ACT-BOOSTER Study)

Inclusion Criteria: In order to be eligible to participate in this study, a subject must meet all of the following criteria: * Age 18-85 years (extremes included), males and females. * Negative SARS-CoV-2 serology (an anti-SARS-CoV-2 SP-specific IgG ELISA) * Body mass index (BMI) between 19.0 and 30.0 kg/m2, inclusive * General good health, without significant medical illness, as determined via physical exam findings, or vital signs * No clinically significant laboratory abnormalities as determined by the investigator o Note: one retest of lab tests is allowed within the screening window * Informed Consent Form signed voluntarily before any study-related procedure is performed, indicating that the subject understands the purpose and procedures required for the study and is willing to participate in the study * Willing to adhere to the prohibitions and restrictions specified in this protocol * All participants have received a completed (registered) vaccine at least 3 months before inclusion in this study (i.e. Pfizer \[Comirnaty\], Moderna \[Spikevax\], Janssen \[Ad26.COV2.S\], AstraZeneca \[Vaxzevria\]). * Negative hepatitis panel (including hepatitis B surface Ag and anti-hepatitis C virus Abs) and negative human immunodeficiency virus Ab and Ag screens at screening * Female subjects should fulfil one of the following criteria: * At least 1 year post-menopausal (amenorrhea \>12 months * Surgically sterile (bilateral oophorectomy, hysterectomy, or tubal ligation); * Will use adequate forms of contraceptives from screening to discharge. * Female subjects of childbearing potential and male subjects who are sexually active with a female partner of childbearing potential must agree to the use of an effective method of birth control from screening to discharge o Note: medically acceptable methods of contraception that may be used by the subject and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, double barrier, sterilization and vasectomy * Female subject has a negative pregnancy test at screening and upon check-in at the clinical site. * Note: pregnancy testing will consist of a serum pregnancy test at screening and urine pregnancy tests at the dosing visit, in all women. Exclusion Criteria: * Pregnant or breast-feeding females * Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, hematologic, rheumatologic, endocrine, autoimmune, or renal disease * Any laboratory test which is abnormal, and which is deemed by the Investigator(s) to be clinically significant * Behavioral or cognitive impairment or psychiatric disease that in the opinion of the investigator affects the ability of the subject to understand and cooperate with the study protocol * Current alcohol/illicit drug/nicotine abuse or addiction: history or evidence of current drug use or addiction (positive drug screen for amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, or opiates) or signs of excessive use of alcohol at screening and at day 0. * Presence of any febrile illness (T \> = 38.0°C or lab confirmed viral disease (PCR)) or symptoms suggestive of a viral respiratory infection within 1 weeks prior to vaccination. Participants will be screened for SARS-Cov-2 with an EUA-approved PCR test at screening, and at day 0. * Use of corticosteroids (excluding topical preparations for cutaneous or nasal use) or use of immunosuppressive drugs within 30 days before inoculation * A history of anaphylaxis, history of allergic reaction to vaccine, known allergy to one of the components in AKS-452X. Mild allergies without angio-edema or treatment need can be included if deemed not to be of clinical significance (including but not limited to allergy to animals or mild seasonal hay fever) * A history of asthma within the past 10 years, or a current diagnosis of asthma or reactive airway disease associated with exercise * Receipt of blood or blood-derived products (including immunoglobulin) within 6 months prior to vaccination. * Receipt of another investigational agent within 30 days or 5 times the product half-life (whichever is longest) prior to vaccination * Deprived of freedom by an administrative or court order or in an emergency setting * Any condition that in the opinion of the principal investigator (PI) would jeopardize the safety or rights of a person participating in the trial or would render the person unable to comply with the protocol.