Healthcare workers and students of Islamic Azad University Tehran Medical Branch(IAUTMU) affiliated hospitals. Age 18-70 years No symptoms of COVID19 at the time of registration No history of COVID-19 diagnosis within the past 3 months from joining the study Desire to participate in the study and filling out the consent form

Healthcare workers and students of Islamic Azad University Tehran Medical Branch(IAUTMU) affiliated hospitals. Age 18-70 years No symptoms of COVID19 at the time of registration No history of COVID-19 diagnosis within the past 3 months from joining the study Desire to participate in the study and filling out the consent form