Heterologous Boost Immunization with Ad5-nCoV After Three-dose Priming with an Inactivated SARS-CoV-2 Vaccine

Immunogenicity and Safety of the Heterologous Prime-boost Immunization with an Adenovirus Type-5 Vector-based COVID-19 Vaccine (Ad5-nCoV) After Three-dose Priming with an Inactivated COVID-19 Vaccine in Adults Aged 18 Years and Above: a Randomized, Open-label, Parallel-controlled Clinical Trial

This is an open-label, randomized, parallel-controlled clinical trial to evaluate the safety and immunogenicity of heterologous prime-boost immunization with an aerosolized (Ad5-nCoV-IH) or intramuscular (Ad5-nCoV-IM) Ad5-nCoV after three-dose priming with an inactivated COVID-19 vaccine (CoronaVac) in adults aged 18 years and above. A total of 360 subjects will be included. Approximately 210 subjects who have completed three doses of CoronaVac more than 6 months ago in the prior clinical trial and other 150 eligible subjects will be recruited and randomized respectively in a ratio of 1:1:1 to receive a booster dose of Ad5-nCoV-IH or Ad5-nCoV-IM or ICV. The occurrence of adverse reactions within 28 days and serious adverse events within 6 months after vaccination will be observed in all participants. In addition, blood and saliva samples will be collected from all participants on the day 0 before and 14, 28 days and 3, 6 months after the booster vaccination. Each subject will remain in this study for approximately 6 months.

Inclusion Criteria:

• Health subjects aged ≥18 years
• The subject can provide with informed consent and sign informed consent form (ICF).
• The subjects are able to and willing to comply with the requirements of the clinical trial program and could complete the 6-month follow-up of the study.
• Participants who have received three-dose of inactivated SARS-CoV-2 vaccine more than 6 months ago.

Exclusion Criteria:

• Have the medical history or family history of convulsion, epilepsy, encephalopathy and psychosis.
• Be allergic to any component of the research vaccines, or used to have a history of hypersensitivity or serious reactions to vaccination.
• Vaccine-related SAE occurred after previous vaccination with COVID-19 vaccine.
• Women with positive urine pregnancy test or in lactation.
• Have acute febrile diseases or infectious diseases or have a history of SARS.
• Axillary temperature>37.0℃
• Have serious cardiovascular diseases, such as arrhythmia, conduction block, myocardial infarction, severe hypertension that cannot be controlled by medication (systolic blood pressure ≥180mmHg and/or diastolic blood pressure ≥110mmHg when measured in the field)
• Have severe chronic diseases or condition is not stable, such as asthma, diabetes, thyroid disease
• Congenital or acquired angioedema / neuroedema.
• Have the history of urticaria 1 year before.
• Have asplenia or functional asplenia.
• Patients with chronic obstructive pulmonary disease, pulmonary fibrosis and other pulmonary abnormalities.
• Have history of SARS-CoV-2 infection or COVID-19.
• Have symptoms of upper respiratory tract infection.
• Have traveled to medium or high risk areas or traveled abroad in the past 21 days, and epidemiologically contacted with SARS-CoV-2.
• Any medical, psychological, social, or other conditions that, in the investigator's judgment, are inconsistent with the protocol or affect the subject's informed consent.