Singapore SARS-CoV-2 Human Challenge Study

The goal of this study is to conduct a safe SARS-CoV-2 Delta variant human infection challenge in adult healthy volunteers. The main objectives are to: * Induce laboratory confirmed infection in up to 70% of participants * Confirm the safety profile as measured by the occurrence of adverse events (AEs) and serious adverse events (SAEs) from the day of viral challenge (Day 0) up to Day 28 follow-up. Participants will be given the GMP-produced Delta SARS-CoV-2 virus via intranasal drops using the optimized conditions established in the "Development of a SARS-CoV-2 Delta variant human infection challenge model" (COVHIC002) Human Challenge Study being conducted in the UK. A safe and well-tolerated human challenge model with the SARS-CoV-2 Delta variant will be established in Singapore. This model will be used to accelerate next-generation vaccine development and to determine the factors associated with altered clinical and virological outcomes; correlates of protection; and targets for the development of novel vaccines, therapeutics, and diagnostics.