* 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.

* 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.

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.

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.