Updated June 17, 2021 at 9:34 AM ET
The Centers for Disease Control and Prevention has declared that the variant of coronavirus first detected in India is a variant of concern, meaning it poses a significant threat to those who are not vaccinated.
The Delta variant, also known as B.1.617.2, is the most contagious yet. The CDC estimates that it may be responsible for nearly 10% of all new COVID-19 infections in the United States. In some Western U.S. states, the variant may be responsible for nearly 20% of cases.