The Delta strain has become the dominant form in the US.
The highly permeable Delta strain has overtaken the alpha version to become the dominant variant in the US, according to new estimates from the US Centers for Disease Control and Prevention (CDC).
The delta, which was first detected in India and now in more than 100 countries, represented 51.7 percent of new infections in the US in the two weeks ended July 3, Xinhua news agency quoted the CDC as saying.
Meanwhile, according to the CDC, the proportion of new cases due to alpha, which was first detected in the UK, was just 28.7 percent over the same time period.
Recently, health officials and experts have warned that the delta variant was on track to become the dominant version in the US, as its prevalence in the nation doubles every two weeks.
They are concerned that the variant will cause a rise in new cases this fall, with unvaccinated populations hitting hardest.
According to the CDC, rising cases were reported in states with low vaccination rates, including Alabama, Arkansas, Louisiana and Mississippi.
Although Delta is highly contagious, research shows that most vaccines are still highly effective in preventing hospitalizations and deaths due to the variant.
US President Joe Biden on Tuesday pushed for all eligible Americans to receive the COVID-19 vaccination, stressing the importance of being protected against Delta.
The country reached its highest vaccination rate in mid-April, when the seven-day average of doses administered daily was about 3.4 million. But the rate has declined since then.
According to CDC data show, about 47.6 percent of the US population has been fully vaccinated against COVID-19, and 55.1 percent of the population has received at least one shot.
Biden set a target in May for 70 percent of American adults to have at least one COVID-19 shot by the Fourth of July. But according to a Forbes report, only 18 states and Washington, DC exceeded that goal.
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