inclusion criteria: * volunteers of both sexes over 18 years of age. * obtaining written informed consent. * ability and consent to participate in this research. * absence of symptoms of respiratory infection. * a negative result of a pcr study for the presence of rna sars-cov-2 according to biomaterial obtained by nasopharyngeal smear.

inclusion criteria: * volunteers of both sexes over 18 years of age. * obtaining written informed consent. * ability and consent to participate in this research. * absence of symptoms of respiratory infection. * a negative result of a pcr study for the presence of rna sars-cov-2 according to biomaterial obtained by nasopharyngeal smear.

inclusion criteria: - volunteers of both sexes over 18 years of age. - obtaining written informed consent. - ability and consent to participate in this research. - absence of symptoms of respiratory infection. - a negative result of a pcr study for the presence of rna sars-cov-2 according to biomaterial obtained by nasopharyngeal smear.

inclusion criteria: - volunteers of both sexes over 18 years of age. - obtaining written informed consent. - ability and consent to participate in this research. - absence of symptoms of respiratory infection. - a negative result of a pcr study for the presence of rna sars-cov-2 according to biomaterial obtained by nasopharyngeal smear.