inclusion criteria: 1. be ≥ 18 years old. 2. indistinct sex. 3. having given their informed consent. 4. no respiratory problems during the last 21 days prior to administration of the single dose. 5. no conditions or alterations in the physical examination, laboratory values and cabinet that in the opinion of the investigator may interfere with the participation of the subject in the study or require a more detailed medical study. 6. negative pcr test for sars-cov-2 during the screening visit. 7. negative pregnancy test in women with pregnancy potential. 8. signature of commitment for the use of highly effective contraceptive methods for at least 30 days after administration of the intramuscular injection or intranasal. 9. in case of presenting any chronic disease with medical management, it must be controlled and stable without changes in treatment during the last three months prior to the scrutiny visit. 10. commitment to maintain adequate prevention measures to avoid the contagion by sars-cov-2 during their participation in the study, considering themselves these strict use during the first 14 days after the baseline visit (use of face masks in closed places, social distancing measures in spaces open, and frequent hand washing). 11. present detectable titers of anti-spike igg in peripheral serum during the visit of screening with titers less than 1,200 u/ml in a chemiluminescence test. 12. submit proof of vaccination 4 months or more after the last vaccination 13. have been vaccinated with the complete program of any of the following vaccines against sars-cov-2: * moderna * pfizer * astrazeneca * cansino * sinovac * sinopharm * johnson \& johnson (janssen) * sputnik v

inclusion criteria: 1. be ≥ 18 years old. 2. indistinct sex. 3. having given their informed consent. 4. no respiratory problems during the last 21 days prior to administration of the single dose. 5. no conditions or alterations in the physical examination, laboratory values and cabinet that in the opinion of the investigator may interfere with the participation of the subject in the study or require a more detailed medical study. 6. negative pcr test for sars-cov-2 during the screening visit. 7. negative pregnancy test in women with pregnancy potential. 8. signature of commitment for the use of highly effective contraceptive methods for at least 30 days after administration of the intramuscular injection or intranasal. 9. in case of presenting any chronic disease with medical management, it must be controlled and stable without changes in treatment during the last three months prior to the scrutiny visit. 10. commitment to maintain adequate prevention measures to avoid the contagion by sars-cov-2 during their participation in the study, considering themselves these strict use during the first 14 days after the baseline visit (use of face masks in closed places, social distancing measures in spaces open, and frequent hand washing). 11. present detectable titers of anti-spike igg in peripheral serum during the visit of screening with titers less than 1,200 u/ml in a chemiluminescence test. 12. submit proof of vaccination 4 months or more after the last vaccination 13. have been vaccinated with the complete program of any of the following vaccines against sars-cov-2: * moderna * pfizer * astrazeneca * cansino * sinovac * sinopharm * johnson \& johnson (janssen) * sputnik v

inclusion criteria: be ≥ 18 years old. indistinct sex. having given their informed consent. no respiratory problems during the last 21 days prior to administration of the single dose. no conditions or alterations in the physical examination, laboratory values and cabinet that in the opinion of the investigator may interfere with the participation of the subject in the study or require a more detailed medical study. negative pcr test for sars-cov-2 during the screening visit. negative pregnancy test in women with pregnancy potential. signature of commitment for the use of highly effective contraceptive methods for at least 30 days after administration of the intramuscular injection or intranasal. in case of presenting any chronic disease with medical management, it must be controlled and stable without changes in treatment during the last three months prior to the scrutiny visit. commitment to maintain adequate prevention measures to avoid the contagion by sars-cov-2 during their participation in the study, considering themselves these strict use during the first 14 days after the baseline visit (use of face masks in closed places, social distancing measures in spaces open, and frequent hand washing). present detectable titers of anti-spike igg in peripheral serum during the visit of screening with titers less than 1,200 u/ml in a chemiluminescence test. submit proof of vaccination 4 months or more after the last vaccination have been vaccinated with the complete program of any of the following vaccines against sars-cov-2: moderna pfizer astrazeneca cansino sinovac sinopharm johnson & johnson (janssen) sputnik v

inclusion criteria: be ≥ 18 years old. indistinct sex. having given their informed consent. no respiratory problems during the last 21 days prior to administration of the single dose. no conditions or alterations in the physical examination, laboratory values and cabinet that in the opinion of the investigator may interfere with the participation of the subject in the study or require a more detailed medical study. negative pcr test for sars-cov-2 during the screening visit. negative pregnancy test in women with pregnancy potential. signature of commitment for the use of highly effective contraceptive methods for at least 30 days after administration of the intramuscular injection or intranasal. in case of presenting any chronic disease with medical management, it must be controlled and stable without changes in treatment during the last three months prior to the scrutiny visit. commitment to maintain adequate prevention measures to avoid the contagion by sars-cov-2 during their participation in the study, considering themselves these strict use during the first 14 days after the baseline visit (use of face masks in closed places, social distancing measures in spaces open, and frequent hand washing). present detectable titers of anti-spike igg in peripheral serum during the visit of screening with titers less than 1,200 u/ml in a chemiluminescence test. submit proof of vaccination 4 months or more after the last vaccination have been vaccinated with the complete program of any of the following vaccines against sars-cov-2: moderna pfizer astrazeneca cansino sinovac sinopharm johnson & johnson (janssen) sputnik v