The COVE study evaluated the efficacy and safety of the mRNA-1273 vaccine in preventing Covid-19. The phase 3 randomized, observer-blinded, placebo-controlled trial enrolled 30,420 participants at high risk for SARS-CoV-2 infection or its complications. Participants were randomly assigned to receive two intramuscular injections of mRNA-1273 (100 μg) or placebo 28 days apart. The primary endpoint was prevention of Covid-19 illness with onset at least 14 days after the second injection in participants who had not previously been infected with SARS-CoV-2. The results showed that the mRNA-1273 vaccine had a 94.1% efficacy in preventing symptomatic Covid-19 illness, including severe disease. Severe Covid-19 occurred in 30 participants, all of whom received the placebo. Moderate, transient reactogenicity after vaccination was more frequent in the mRNA-1273 group, but serious adverse events were rare and similar between the two groups. The study concluded that the mRNA-1273 vaccine is effective and safe for preventing Covid-19, with no significant safety concerns identified aside from transient local and systemic reactions.The COVE study evaluated the efficacy and safety of the mRNA-1273 vaccine in preventing Covid-19. The phase 3 randomized, observer-blinded, placebo-controlled trial enrolled 30,420 participants at high risk for SARS-CoV-2 infection or its complications. Participants were randomly assigned to receive two intramuscular injections of mRNA-1273 (100 μg) or placebo 28 days apart. The primary endpoint was prevention of Covid-19 illness with onset at least 14 days after the second injection in participants who had not previously been infected with SARS-CoV-2. The results showed that the mRNA-1273 vaccine had a 94.1% efficacy in preventing symptomatic Covid-19 illness, including severe disease. Severe Covid-19 occurred in 30 participants, all of whom received the placebo. Moderate, transient reactogenicity after vaccination was more frequent in the mRNA-1273 group, but serious adverse events were rare and similar between the two groups. The study concluded that the mRNA-1273 vaccine is effective and safe for preventing Covid-19, with no significant safety concerns identified aside from transient local and systemic reactions.