Variants of concern have emerged in Brazil, the United Kingdom and South Africa. The delta variant was identified in India in December 2020 and was first detected in the U.S. in March, according to the U.S. Centers for Disease Control and Prevention. It was first detected in Arkansas at the beginning of May, according to the state Health Department, which conducts genetic sequencing of samples of the virus on a routine basis to determine which variants are making inroads. The sequencing of the covid-19 positive samples can take from about a week to nearly a month, depending on where the samples are sent and national backlogs.