inclusion criteria: * signed informed consent * healthy male or female aged 18 - 60 years (including both groups) * subjects who were vaccinated with coronavac for 2 doses and who had a minimum of 90 days and a maximum of 270 days after the second dose * subjects may have a controlled or moderate comorbidity * female subjects of childbearing potential should be willing to ensure that they or their partner use effective birth control methods continuously from 1 month before and up to 3 months after vaccination * subjects agreed to comply with all study requirements * subjects are willing to share their medical history with their physician and allow access to all medical records when relevant to study procedures * subjects are willing to agree to abstain from donating blood during the study

inclusion criteria: * signed informed consent * healthy male or female aged 18 - 60 years (including both groups) * subjects who were vaccinated with coronavac for 2 doses and who had a minimum of 90 days and a maximum of 270 days after the second dose * subjects may have a controlled or moderate comorbidity * female subjects of childbearing potential should be willing to ensure that they or their partner use effective birth control methods continuously from 1 month before and up to 3 months after vaccination * subjects agreed to comply with all study requirements * subjects are willing to share their medical history with their physician and allow access to all medical records when relevant to study procedures * subjects are willing to agree to abstain from donating blood during the study

inclusion criteria: - signed informed consent - healthy male or female aged 18 - 60 years (including both groups) - subjects who were vaccinated with coronavac for 2 doses and who had a minimum of 90 days and a maximum of 270 days after the second dose - subjects may have a controlled or moderate comorbidity - female subjects of childbearing potential should be willing to ensure that they or their partner use effective birth control methods continuously from 1 month before and up to 3 months after vaccination - subjects agreed to comply with all study requirements - subjects are willing to share their medical history with their physician and allow access to all medical records when relevant to study procedures - subjects are willing to agree to abstain from donating blood during the study

inclusion criteria: - signed informed consent - healthy male or female aged 18 - 60 years (including both groups) - subjects who were vaccinated with coronavac for 2 doses and who had a minimum of 90 days and a maximum of 270 days after the second dose - subjects may have a controlled or moderate comorbidity - female subjects of childbearing potential should be willing to ensure that they or their partner use effective birth control methods continuously from 1 month before and up to 3 months after vaccination - subjects agreed to comply with all study requirements - subjects are willing to share their medical history with their physician and allow access to all medical records when relevant to study procedures - subjects are willing to agree to abstain from donating blood during the study