inclusion criteria: participants must meet all of the following criteria to be eligible for inclusion in this phase i study. i. men and women ≥ 18 years to ≤ 55 years of age; ii. must be generally healthy as confirmed by a medical history and physical examination for study entry; iii. subjects who have not been previously immunized with any sars-cov-2 vaccine or subjects who have been immunized with sars-cov-2 vaccine based inactivated virus technology at least 3 months from the administration of the second dose and have neutralizing antibody titers less than or equal to 40% in plasma samples tested at 1:40 dilution; iv. women of childbearing age and of childbearing potential must present during the screening period and on the day of each vaccination the result of a pregnancy test (serum test) with a negative result, as well as not be breastfeeding; in addition, to enroll in the study as volunteers, women who have sex with men must necessarily use one of the contraceptive methods listed below at the time of enrollment and up to 60 days after the last injection of the vaccine (this 60-day interval has been defined as a safety criterion): hormonal (e.g., oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or intrauterine system (ius); vasectomized (6 months minimum) or abstinent partner; bilateral tubal ligation (if no conception post-procedure); tubal occlusion or bilateral salpingectomy. these precautions are necessary because of unknown effects that vaccine rna mcti cimatec hdt may cause in a fetus or newborn. women will be considered out of the potential to become pregnant if they are postmenopausal (defined as spontaneous amenorrhea of at least 12 months and confirmed with follicle-stimulating hormone concentrations >40 mui/ml) or have documented hysterectomy and/or oophorectomy; and, non-sterile men who agree to use adequate contraception with their partner during and up to 60 days after the last injection of the study vaccine; v. the following laboratory test values for screening must be within normal limits or not clinically significant, as determined by the researcher and approved by the medical monitor: sodium, potassium, glutamic-oxalacetic transaminase (got), glutamic-pyruvic transaminase (gpt), total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at the discretion of the researcher; vi. the following serological tests must be negative: hiv 1/2 antibody, hepatitis b surface antigen (hbsag) and hepatitis c virus (hcv) antibody; vii. negative test for recreational drugs and alcohol according to the standards of the clinical research unit; viii. normal or not clinically significant urine test as determined by the clinician or designee. abnormal results may be repeated at the discretion of the researcher; ix. must present blood count within normal limits up to 10 days prior to administration of the first dose of the vaccine rna mcti cimatec hdt; x. must present negative rt-pcr test for sars-cov-2 24 to 48 h before administration of the study vaccine and absence of signs and symptoms compatible with covid-19 (e.g. fever, cough, shortness of breath, chills, etc.); xi. must be able to complete the mnemonic adverse event questionnaire (mmea) (appendix 1); xii. must give informed consent, be able and willing to make all evaluation visits, be accessible by phone or personal contact by the local study team, and have a permanent address.

inclusion criteria: participants must meet all of the following criteria to be eligible for inclusion in this phase i study. i. men and women ≥ 18 years to ≤ 55 years of age; ii. must be generally healthy as confirmed by a medical history and physical examination for study entry; iii. subjects who have not been previously immunized with any sars-cov-2 vaccine or subjects who have been immunized with sars-cov-2 vaccine based inactivated virus technology at least 3 months from the administration of the second dose and have neutralizing antibody titers less than or equal to 40% in plasma samples tested at 1:40 dilution; iv. women of childbearing age and of childbearing potential must present during the screening period and on the day of each vaccination the result of a pregnancy test (serum test) with a negative result, as well as not be breastfeeding; in addition, to enroll in the study as volunteers, women who have sex with men must necessarily use one of the contraceptive methods listed below at the time of enrollment and up to 60 days after the last injection of the vaccine (this 60-day interval has been defined as a safety criterion): hormonal (e.g., oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or intrauterine system (ius); vasectomized (6 months minimum) or abstinent partner; bilateral tubal ligation (if no conception post-procedure); tubal occlusion or bilateral salpingectomy. these precautions are necessary because of unknown effects that vaccine rna mcti cimatec hdt may cause in a fetus or newborn. women will be considered out of the potential to become pregnant if they are postmenopausal (defined as spontaneous amenorrhea of at least 12 months and confirmed with follicle-stimulating hormone concentrations >40 mui/ml) or have documented hysterectomy and/or oophorectomy; and, non-sterile men who agree to use adequate contraception with their partner during and up to 60 days after the last injection of the study vaccine; v. the following laboratory test values for screening must be within normal limits or not clinically significant, as determined by the researcher and approved by the medical monitor: sodium, potassium, glutamic-oxalacetic transaminase (got), glutamic-pyruvic transaminase (gpt), total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at the discretion of the researcher; vi. the following serological tests must be negative: hiv 1/2 antibody, hepatitis b surface antigen (hbsag) and hepatitis c virus (hcv) antibody; vii. negative test for recreational drugs and alcohol according to the standards of the clinical research unit; viii. normal or not clinically significant urine test as determined by the clinician or designee. abnormal results may be repeated at the discretion of the researcher; ix. must present blood count within normal limits up to 10 days prior to administration of the first dose of the vaccine rna mcti cimatec hdt; x. must present negative rt-pcr test for sars-cov-2 24 to 48 h before administration of the study vaccine and absence of signs and symptoms compatible with covid-19 (e.g. fever, cough, shortness of breath, chills, etc.); xi. must be able to complete the mnemonic adverse event questionnaire (mmea) (appendix 1); xii. must give informed consent, be able and willing to make all evaluation visits, be accessible by phone or personal contact by the local study team, and have a permanent address.

inclusion criteria: males and females between 18 years and 55 years of age. must be in good general health as confirmed by a medical history and physical exam. female subjects of childbearing potential must have a negative serum pregnancy test at screening and on the day of each study vaccination and must not be breast-feeding.those that have sexual relationships with men are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection: hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that vacina rna mcti cimatec hdt might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy and non-sterile men who agree to use proper contraception with their partner during and up to 30 days after the last injection of study vaccine; the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. negative test for recreational drugs and alcohol per clinical research unit standards. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. normal blood count within 10 days before the administration of the first dose of the vacina rna mcti cimatec hdt vaccine. must be capable of completing the adverse event mnemonic questionnaire. must have negative rt-pcr test for sars-cov-2 24 to 48 h before administration of study vaccine and absence of signs and symptoms compatible with covid-19 (eg, fever, cough, shortness of breath, chills,etc.); must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -

inclusion criteria: males and females between 18 years and 55 years of age. must be in good general health as confirmed by a medical history and physical exam. female subjects of childbearing potential must have a negative serum pregnancy test at screening and on the day of each study vaccination and must not be breast-feeding.those that have sexual relationships with men are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection: hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that vacina rna mcti cimatec hdt might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy and non-sterile men who agree to use proper contraception with their partner during and up to 30 days after the last injection of study vaccine; the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. negative test for recreational drugs and alcohol per clinical research unit standards. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. normal blood count within 10 days before the administration of the first dose of the vacina rna mcti cimatec hdt vaccine. must be capable of completing the adverse event mnemonic questionnaire. must have negative rt-pcr test for sars-cov-2 24 to 48 h before administration of study vaccine and absence of signs and symptoms compatible with covid-19 (eg, fever, cough, shortness of breath, chills,etc.); must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -

inclusion criteria: 1. males and females between 18 years and 55 years of age. 2. must be in good general health as confirmed by a medical history and physical exam. 3. female subjects of childbearing potential must have a negative serum pregnancy test at screening and on the day of each study vaccination and must not be breast-feeding.those that have sexual relationships with men are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection: hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that vacina rna mcti cimatec hdt might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy and non-sterile men who agree to use proper contraception with their partner during and up to 30 days after the last injection of study vaccine; 4. the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. 5. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. 6. negative test for recreational drugs and alcohol per clinical research unit standards. 7. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. 8. normal blood count within 10 days before the administration of the first dose of the vacina rna mcti cimatec hdt vaccine. 9. must be capable of completing the adverse event mnemonic questionnaire. 10. must have negative rt-pcr test for sars-cov-2 24 to 48 h before administration of study vaccine and absence of signs and symptoms compatible with covid-19 (eg, fever, cough, shortness of breath, chills,etc.); 11. must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -

inclusion criteria: 1. males and females between 18 years and 55 years of age. 2. must be in good general health as confirmed by a medical history and physical exam. 3. female subjects of childbearing potential must have a negative serum pregnancy test at screening and on the day of each study vaccination and must not be breast-feeding.those that have sexual relationships with men are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection: hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that vacina rna mcti cimatec hdt might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy and non-sterile men who agree to use proper contraception with their partner during and up to 30 days after the last injection of study vaccine; 4. the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. 5. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. 6. negative test for recreational drugs and alcohol per clinical research unit standards. 7. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. 8. normal blood count within 10 days before the administration of the first dose of the vacina rna mcti cimatec hdt vaccine. 9. must be capable of completing the adverse event mnemonic questionnaire. 10. must have negative rt-pcr test for sars-cov-2 24 to 48 h before administration of study vaccine and absence of signs and symptoms compatible with covid-19 (eg, fever, cough, shortness of breath, chills,etc.); 11. must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -

inclusion criteria: 1. males and females between 18 years and 55 years of age. 2. must be in good general health as confirmed by a medical history and physical exam. 3. female subjects of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test on the day of each study vaccination, must not be breast-feeding, and are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection (only if in sexual relationships with men): hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that hdt-301 might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy. 4. the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. 5. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. 6. negative test for recreational drugs and alcohol per clinical research unit standards. 7. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. 8. normal blood count within 10 days before the administration of the first dose of the hdt-301 vaccine. 9. must be capable of completing a study memory aid in english. 10. must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -

inclusion criteria: 1. males and females between 18 years and 55 years of age. 2. must be in good general health as confirmed by a medical history and physical exam. 3. female subjects of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test on the day of each study vaccination, must not be breast-feeding, and are required to use one of the following methods of contraception from enrollment in study until 30 days after last injection (only if in sexual relationships with men): hormonal (e.g. oral, transdermal, intravaginal, implant, or injection); double barrier (i.e., condom, diaphragm, or cervical cap with spermicide); intrauterine device (iud) or system (ius); vasectomized partner (6 months minimum); or abstinence; bilateral tubal ligation (if no conception post-procedure); tubal occlusion; or bilateral salpingectomy. these precautions are necessary due to unknown effects that hdt-301 might cause in a fetus or newborn infant. women are considered non-child-bearing potential if they are post-menopausal (defined as at least 12 months spontaneous amenorrhea and confirmed with fsh > 40 miu/ml) or have had documented hysterectomy and/or oophorectomy. 4. the following screening laboratory values must be within the normal ranges or not clinically significant as determined by the investigator and approved by the medical monitor: sodium, potassium, bun, alt, ast, total bilirubin, alkaline phosphatase, creatinine, fasting glucose, total wbc count, hemoglobin, and platelet count. abnormal results may be repeated once for confirmation at investigator discretion. 5. the following serology tests must be negative: sars-cov-2 antibody, hiv 1/2 antibody, hepatitis b surface antigen (hbsag), and hepatitis c virus (hcv) antibody. 6. negative test for recreational drugs and alcohol per clinical research unit standards. 7. normal or not clinically significant urinalysis as determined by the study clinician or designee. abnormal results may be repeated at investigator discretion. 8. normal blood count within 10 days before the administration of the first dose of the hdt-301 vaccine. 9. must be capable of completing a study memory aid in english. 10. must give informed consent, be able and willing to make all evaluation visits, be reachable by telephone or personal contact by the study site personnel, and have a permanent address. -