1. 18 years old or more 2. No history of a severe allergic reaction to the prior vaccine. 3. No fever nor history of fever within 14 days. 4. No symptoms of respiratory tract infection within 14 days. 5. Received two doses of COVID-19 vaccine for at least 3 months 6. sign informed consent to the study.

1. 18 years old or more 2. No history of a severe allergic reaction to the prior vaccine. 3. No fever nor history of fever within 14 days. 4. No symptoms of respiratory tract infection within 14 days. 5. Received two doses of COVID-19 vaccine for at least 3 months 6. sign informed consent to the study.