Delta COVID-19 variant now likely dominant in US, CDC says

The Delta COVID-19 variant is now the likely dominant strain in the U.S., overtaking Alpha to account for 51.7% of infections, according to the latest data from the Centers for Disease Control and Prevention (CDC).

The Alpha variant, which had been the dominant strain for the last several months, is now thought to account for about 28.7% of cases, the CDC said.

Health officials had predicted that the Delta variant, or B.1.617.2, would unseat Alpha as the most dominant strain in a matter of weeks, as the more transmissible strain was doubling at a rate of every two weeks. It’s estimated to spread 40-60% more readily than the Alpha variant and appears "fitter and faster" due to several acquired mutations, one expert previously told Fox News. 

The variant has been of particular concern for health officials in regions with low vaccination rates, particularly in the Midwest. 

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The White House announced it would be sending "surge response" teams to areas seeing a spike in Delta cases, with the first arriving in Springfield, Missouri, on Wednesday. The two-person team is reportedly committed to staying in the area through Aug. 6. 

The number of hospitalized COVID-19 patients increased by nearly 27% over the weekend, with at least one hospital running out of ventilators. The White House COVID-19 response team, which is holding a briefing again Thursday, has long warned that the variant poses a threat to progress made against coronavirus. 

However, Dr. Rochelle Walensky, director of the CDC, and Dr. Anthony Fauci, the nation’s leading infectious disease expert, have repeatedly stated that authorized vaccines remain effective against the variant. 

"Currently, approximately 1,000 counties in the United States have vaccination coverage of less than 30%," Walensky said in a briefing last week. "These communities, primarily in the Southeast and Midwest, are our most vulnerable. In some of these areas, we are already seeing increasing rates of disease. As the Delta variant continues to spread across the country, we expect to see increased transmissions in these communities, unless we can vaccinate more people now." 

Some regions, such as Los Angeles, have pushed for more COVID-19 restrictions, such as a return to wearing face masks for fully vaccinated people, while others say the true risk is for unvaccinated individuals. 

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"While 40-60% more contagious, the COVID in all its variant forms is circulating at very low levels in the population," Dr. Marty Makary, Fox News contributor and Johns Hopkins surgeon, previously said. "The only people who should be concerned are those who do not have immunity either through vaccination or natural immunity. At this point, everyone at-risk has had the opportunity to get vaccinated. Those who are not immune are choosing to do so at their own personal risk." 

The Associated Press contributed to this report.