inclusion criteria: 1. healthy subjects aged 3 to 17 years who can provide vaccination information proving that they have received two doses of commercially available novel coronavirus inactivated vaccine in the last 6-9 months; 2. the subject voluntarily agrees to participate in the study (and/or the subject's legal guardian voluntarily agrees to allow the child to participate in the study), and the guardian and the subject (aged 8-17) sign the informed consent, and can provide valid identification; understand and comply with test protocol requirements; 3. armpit temperature \< 37.3℃ (\> 14 years old), armpit temperature \< 37.5℃ (≤14 years old); 4. female subjects of reproductive age agree to use effective contraceptive measures from the beginning to the end of the study.

inclusion criteria: 1. healthy subjects aged 3 to 17 years who can provide vaccination information proving that they have received two doses of commercially available novel coronavirus inactivated vaccine in the last 6-9 months; 2. the subject voluntarily agrees to participate in the study (and/or the subject's legal guardian voluntarily agrees to allow the child to participate in the study), and the guardian and the subject (aged 8-17) sign the informed consent, and can provide valid identification; understand and comply with test protocol requirements; 3. armpit temperature \< 37.3℃ (\> 14 years old), armpit temperature \< 37.5℃ (≤14 years old); 4. female subjects of reproductive age agree to use effective contraceptive measures from the beginning to the end of the study.

inclusion criteria: healthy subjects aged 3 to 17 years who can provide vaccination information proving that they have received two doses of commercially available novel coronavirus inactivated vaccine in the last 6-9 months; the subject voluntarily agrees to participate in the study (and/or the subject's legal guardian voluntarily agrees to allow the child to participate in the study), and the guardian and the subject (aged 8-17) sign the informed consent, and can provide valid identification; understand and comply with test protocol requirements; armpit temperature < 37.3℃ (> 14 years old), armpit temperature < 37.5℃ (≤14 years old); female subjects of reproductive age agree to use effective contraceptive measures from the beginning to the end of the study.

inclusion criteria: healthy subjects aged 3 to 17 years who can provide vaccination information proving that they have received two doses of commercially available novel coronavirus inactivated vaccine in the last 6-9 months; the subject voluntarily agrees to participate in the study (and/or the subject's legal guardian voluntarily agrees to allow the child to participate in the study), and the guardian and the subject (aged 8-17) sign the informed consent, and can provide valid identification; understand and comply with test protocol requirements; armpit temperature < 37.3℃ (> 14 years old), armpit temperature < 37.5℃ (≤14 years old); female subjects of reproductive age agree to use effective contraceptive measures from the beginning to the end of the study.