The delta variant now accounts for more than 83% of new cases of Covid-19, said Dr Rochelle Walensky, director of the Centers for Disease Control and Prevention, on Tuesday.
Walensky spoke at a hearing of the Senate Committee on Health, Education, Labor and Pensions.
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As of July 17, the latest date for which data were available, the delta variant represented 83.2% of new cases of Covid-19 that had been genetically sequenced in the country. The CDC is expected to release these latest statistics online Tuesday afternoon.
The increase in the delta variant coincides with a sharp increase in Covid-19 cases, hospitalizations and deaths nationwide in the United States, the CDC said last week.
The increase in cases involving the “hypertransmissible” variant was not unexpected. These infections were expected to double every few weeks.
Just a month ago, on June 19, the delta variant accounted for just over 30% of new cases. On July 3, it crossed the 50% threshold to become the dominant variant in the country.
Studies have shown that Covid-19 vaccines are effective against several variants, including the delta variant.
But the new data comes as vaccinations in the United States have slowed. As of Tuesday, less than half of the country’s population – 48.6% – was fully vaccinated.
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Those who are not vaccinated are most at risk of infection. This includes children under 12, for whom no vaccine is available. There is no evidence that the variant hits children harder, other than the fact that they are vulnerable because they cannot yet be vaccinated.
“We’re going to see a pediatric Covid,” said Dr Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. “I think part of a strong acceleration of the delta variant is going to take the kids with it.”
Authorization for emergency use of vaccines for children may not be available until the middle of winter, a Food and Drug Administration official recently told NBC News.
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