BBV152/BBV154 Heterologus Prime-Boost Study

All participants will be assessed for immunogenicity and safety endpoints and provide a blood sample before the administration of the first dose of IP. Blood samples will be collected on days 0, 9 (Groups 1, 3 and 4), 28,37 (Groups 2 and 4), 56, 90 and 180 to assess the neutralizing antibody titer against the SARSCoV-2 virus. A subset of 160 Participants (40 participants from each group) will be assessed for immunogenicity analysis, among these subset 10mL of blood and 5mL of saliva will be collected on days 0, 9 (Groups 1, 3 and 4), 28, 37 (Groups 2 and 4), 56, 90 and 180 to assess cell-mediated immunity and mucosal immunogenicity.Group 1 (COVAXIN® + COVAXIN®): In this group, 152 participants will be recruited who will receive COVAXIN® on day 0 and on day 28 via the intramuscular route.Group 2 (COVAXIN® + BBV154): In this group, 152 participants will be recruited who will receive COVAXIN® (Intramuscular) on day 0 and BBV154 (Intranasal) day 28.*Post 56 days of vaccination, participants with seroconversion rate less than 3 folds will receive another dose of COVAXIN® viaintramuscular route.Group 3 (BBV154 + COVAXIN®): In this group, 152 participants will be recruited who will receive BBV154 (Intranasal) on day 0 and COVAXIN® (Intramuscular) on day 28.*Post 56 days of vaccination, participants with seroconversion rate less than 3 folds will receive another dose of COVAXIN® via intramuscular route.Group 4 (BBV154 + BBV154): In this group, 152 participants will be recruited who will receive BBV154 on day 0 and on day 28 via the intranasal route.

Inclusion Criteria:Ability to provide written informed consent.Participants of either gender, ages between 18 years <65 Years.Good general health as determined by the discretion of investigator (vital signs (heart rate 60 to 100 bpm; blood pressure systolic 90 mm Hg and <140 mm Hg; diastolic 60 mm Hg and <90 mm Hg; oral temperature <100.4ºF), medical history, and physical examination).Expressed interest and availability to fulfil the study requirements.For a female participant of child-bearing potential, planning to avoid becoming pregnant (use of an effective method of contraception or abstinence) from the time of study enrolment until at least four weeks after the last vaccinationMale subjects of reproductive potential: Use of condoms to ensure effective contraception with the female partner from first vaccination until 3 months after last vaccination .Participants must refrain from blood/plasma or any other bodily fluid donation from the time of first vaccination until 3 months after the last vaccinationAgrees not to participate in another clinical trial at any time during the study period.Agrees to remain in the study area for the entire duration of the study.Willing to allow storage and future use of biological samples for future researchExclusion Criteria:History of any other COVID-19 investigational/or licensed vaccination.History of cold, sneezing, nasal obstruction in the past 1 day.For women of childbearing potential, a positive urine pregnancy test (within 24 hours of administering each dose of vaccine).Temperature >38.0°C (100.4°F) or symptoms of an acute self-limited illness such as an upper respiratory infection or gastroenteritis within three days before each dose of vaccine.Medical problems because of alcohol or illicit drug use during the past 12 months.Receipt of an experimental agent (vaccine, drug, device, etc.) within 60 days before enrolment or expects to receive an investigational agent during the study period.Receipt of any licensed vaccine within four weeks before enrolment in this study.Known sensitivity to any ingredient of the study vaccines, or a more severe allergic reaction and history of allergies in the past.Receipt of immunoglobulin or other blood products within the three months before vaccination in this study.Immunosuppression as a result of an underlying illness or treatment with immunosuppressive or cytotoxic drugs, or use of anticancer chemotherapy or radiation therapy within the preceding 36 months.Long-term use (> 2 weeks) of oral or parenteral steroids (glucocorticoids) or high-dose inhaled steroids (>800 mcg/day of beclomethasone dipropionate or equivalent) within the preceding six months (nasal and topical steroids are allowed).Any history of anaphylaxis concerning vaccination.History of any cancer.History of severe psychiatric severe conditions likely to affect participation in the study.A bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder, or prior history of significant bleeding or bruising following IM injections or venipuncture.Any other serious chronic illness requiring immediate hospital specialist supervision.Any other condition that in the opinion of the investigator would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol. Re-Vaccination Exclusion CriteriaPregnancy.Anaphylactic reaction following administration of the vaccine.Virologically confirmed cases of SARS-CoV-2 infection.