Title: A phase 2/3, observer-blind, randomized, controlled study to determine the safety and immunogenicity of Covishield (Covid-19 vaccine) in healthy Indian adults(Covishield study)

Sponsor: Serum Institute of India Private Limited (Siipl)

Co-Sponsor: Indian Council of Medical Research (ICMR)

Study Design: Observer -blind, Randomized, controlled, Multicentric Study

Safety Cohort: Covishield (SII-ChAdOx1 nCoV-19) OR Placebo

Immunogenicity Cohort: Covishield (SII-ChAdOx1 nCoV-19) OR Oxford/AZ-ChAdOx1 nCoV-19

Condition: Prevention of COVID-19

Objectives: a. To assess the Safety Covishield b. To assess immunogenicity of Covishield in comparison with the Oxford/AZChAdOx1 nCoV-19 vaccine by IgG ELISA assay.

Study Initiation date: 26-Aug-2020

Study population: 1600 healthy volunteers

Study duration: 7 months

Introduction and rational of the study: The COVID-19 epidemic has caused major disruption to healthcare systems with significant socioeconomic impacts. Containment measureshave failed to stop the spread of virus, which has reached pandemic levels.There are currently no specific treatments available against COVID-19 and accelerated vaccine development is urgently needed.Live attenuated viruses have historically been among the mostimmunogenic platforms available, as they have the capacity to presentmultiple antigens across the viral life cycle in their native conformations. However, manufacturing live attenuated viruses requires complexcontainment and biosafety measures. Furthermore, live-attenuated virusescarry the risks of inadequate attenuation causing disseminated disease,particularly in immunocompromised hosts. Given that severe disease andfatal COVID-19 disproportionally affect older adults with co-morbidities,making a live- attenuated virus vaccine is a less viable option. Replication competent viral vectors could pose a similar threat for disseminated disease in the immuno-suppressed. Replication deficientvectors, however, avoid that risk while maintaining the advantages ofnative antigen presentation, elicitation of T cell immunity and the abilityto express multiple antigens.Subunit vaccines usually require the use of adjuvants and whilst DNA and RNA vaccines can offer manufacturing advantages, they are often poorlyimmunogenic requiring multiple doses, which is highly undesirable in thecontext of a pandemic.Chimpanzee adenovirus (ChAd) vaccine vectors have been safelyadministered to thousands of people using a wide range of infectious.

Current status of the study: Completed