A Clinical trial of Omicron-Based CovIran Barkat vaccine as a third injection dose in vaccinated population over 18 years of age

INTERVENTION: Intervention 1: Group of recipients of the third injection of CovIran Barkat vaccine of Wuhan strain, with a history of receiving two doses of CovIran Barkat vaccine. Intervention 2: Group of recipients of the third injection of CovIran Barkat vaccine of Omicron strain, with a history of receiving two doses of CovIran Barkat vaccine. Intervention 3: Group of recipients of the third injection of CovIran Barkat vaccine of Omicron strain, with a history of receiving two doses of Sinopharm vaccine. CONDITION: COVID‐19 disease. ; COVID‐19, virus identified U07.1 PRIMARY OUTCOME: Anti‐Spike, Neutralizing Antibody, Anti‐RBD titres (with GMT , GMI). Timepoint: Days 0,14, 90, 180. Method of measurement: ELISA assay. Seroconversion rate (Anti‐Spike, Neutralizing, Anti‐RBD). Timepoint: Days 0,14, 90, 180. Method of measurement: ELISA assay. SECONDARY OUTCOME: Any immediate reaction after inoculation. Timepoint: 0‐30 minutes after inoculation. Method of measurement: Close observation. Occurrence of any systemic events. Timepoint: Days 0 to 180 after inoculation. Method of measurement: Examination, history, and report of the study participant based on the Vaccine Adverse Event Reporting System. Lymphocytes subset count and cytokines for determining cellular immunity. Timepoint: Days 0, 14, 90, 180. Method of measurement: ELISA assay. Percentage of systemic events (fever, headache, chills, nausea, vomiting, diarrhoea, fatigue, muscle pain, arthralgia, ....). Timepoint: Days 0 to 7 after inoculation. Method of measurement: Examination, history, and report of the study participant based on the Vaccine Adverse Event Reporting System. Occurrence of any adverse event (serious or non‐serious). Timepoint: Days 0 to 7 after inoculation. Method of measurement: Examination, history, and report of the study participant based on the Vaccine Adverse Event Reporting System. Occurrence and the severity of SARS‐COV‐2 infection. Timepoint: Till 180 days after inoculation. Method of measurement: Comparing confirmed COVID‐19 cases, severity status is categorised as non‐severe, severe, and critical based on the WHO diagnosis scheme. Percentage of local reactions (pain, redness, swelling, ....in injection site). Timepoint: Days 0 to 7 after each inoculation. Method of measurement: Examination, history, and report of the study participant based on the Vaccine Adverse Event Reporting System. Occurrence of any adverse event (serious or non‐serious). Timepoint: Days 0 to 180 after inoculation. Method of measurement: Examination, history, and report of the study participant based on the Vaccine Adverse Event Reporting System. INCLUSION CRITERIA: Aged over 18 years old In the volunteer’s vaccination history, the interval between the first and second dose is between 4 to 8 weeks and at least 3 months and at most 5 months have passed since the injection of the second dose of the volunteer's vaccination. The volunteer must be able and willing to cooperate with the researchers throughout the study period. The volunteer must be able to fully understand the executive processes of the study and to understand the explanations of the facilitators correctly. The volunteer would be able to understand the contents of the informed consent form and sign the informed consent before recruitment. Access to the medical records and test results if hospitalised for any reason including due to the suspected or confirmed COVID‐19 should be allowed. The volunteer has been in a medically stable condition for the past three months (he/she has not been hospitalized, his / her chronic illness has not recurred). His /