Results from a Phase 3 clinical trial enrolling 29,960 adult volunteers in the United States and Mexico show that the investigational vaccine known as NVX-CoV2373 demonstrated 90.4% efficacy in preventing symptomatic COVID-19 disease. The candidate showed 100% protection against moderate and severe disease. In people at high risk of developing complications from COVID-19 (people 65 years or older and people under age 65 with certain comorbidities or with likely regular exposure to COVID-19), the vaccine showed 91.0% efficacy in preventing symptomatic COVID-19 disease.