inclusion criteria: * persons who have received a dose of gam-covid-vac more than 30 days and less than 90 days ago. * age \> 65 years. * both genders. * who have voluntarily agreed to participate in the clinical trial and have provided informed consent.

inclusion criteria: * persons who have received a dose of gam-covid-vac more than 30 days and less than 90 days ago. * age \> 65 years. * both genders. * who have voluntarily agreed to participate in the clinical trial and have provided informed consent.

inclusion criteria: - persons who have received a dose of gam-covid-vac more than 30 days and less than 90 days ago. - age > 65 years. - both genders. - who have voluntarily agreed to participate in the clinical trial and have provided informed consent.

inclusion criteria: - persons who have received a dose of gam-covid-vac more than 30 days and less than 90 days ago. - age > 65 years. - both genders. - who have voluntarily agreed to participate in the clinical trial and have provided informed consent.