The head of the U.S. Centers for Disease Control and Prevention (CDC) said the “Delta” variant of COVID-19 could become the most common strain of the virus in the United States. “It’s more transmissible than the Alpha variant, or the UK variant, that we have here,” Dr. Rochelle Walensky told ABC News last week. “We saw that quickly become the dominant strain in a period of one or two months, and I anticipate that is going to be what happens with the Delta strain here.” Health officials, including Walensky, have said that current COVID-19 vaccines remain effective against the strain. The Delta variant, also known as B.1.617.2, was first identified late last year. Officials said that it spread rapidly throughout India earlier this year before spreading to dozens of other countries. President Joe Biden, meanwhile said he doesn’t believe the Delta variant will prompt lockdowns like the ones that were …