inclusion criteria: * 18 years of age or older, vaccinated with 1 dose of sputnik v, astrazeneca or sinopharm vaccine up to 60 days prior to enrollment (according to the platform of the vaccine received as the first dose) or not vaccinated for the mrna-1273 / mrna-1273 arm * with and without identified risk factors for covid-19 * signature of the informed consent * remain in the jurisdiction where your study began until the end of it * be able to understand and sign the informed consent

inclusion criteria: * 18 years of age or older, vaccinated with 1 dose of sputnik v, astrazeneca or sinopharm vaccine up to 60 days prior to enrollment (according to the platform of the vaccine received as the first dose) or not vaccinated for the mrna-1273 / mrna-1273 arm * with and without identified risk factors for covid-19 * signature of the informed consent * remain in the jurisdiction where your study began until the end of it * be able to understand and sign the informed consent

inclusion criteria: - 18 years of age or older, vaccinated with 1 dose of sputnik v, astrazeneca or sinopharm vaccine up to 60 days prior to enrollment (according to the platform of the vaccine received as the first dose) or not vaccinated for the mrna-1273 / mrna-1273 arm - with and without identified risk factors for covid-19 - signature of the informed consent - remain in the jurisdiction where your study began until the end of it - be able to understand and sign the informed consent

inclusion criteria: - 18 years of age or older, vaccinated with 1 dose of sputnik v, astrazeneca or sinopharm vaccine up to 60 days prior to enrollment (according to the platform of the vaccine received as the first dose) or not vaccinated for the mrna-1273 / mrna-1273 arm - with and without identified risk factors for covid-19 - signature of the informed consent - remain in the jurisdiction where your study began until the end of it - be able to understand and sign the informed consent