(Reuters) – The highly transmissible coronavirus variants first identified in India and Brazil, now known as Delta and Gamma, respectively, are quickly displacing the Alpha (UK) variant as the most common in the United States, according to a large new study of positive COVID-19 tests from across the country.
The percentage of COVID-19 cases due to Alpha dropped from 70% in mid-April 2021 to 42% just 6 weeks later, researchers from Helix, a California-based genomics company, reported in a paper posted on medRxiv ahead of peer review.
The Gamma and Delta variants were “the primary drivers for this displacement,” the researchers said.
The growth rate of Delta is higher than that of Gamma and is particularly high in counties with vaccination rates below 28.5%, they found.
Delta has been widely reported to be even more transmissible than Alpha and to cause more severe disease and hospitalizations.
“The expectation is that (Delta) will soon be the dominant variant in the United States,” the authors said.
SOURCE: https://bit.ly/3x45vBW medRxiv, online June 21, 2021.