Mario Tama/Getty Images
- The Financial Times estimates the Delta variant made up a third of US COVID-19 cases as of last week.
- That would mean the variant's share of infections tripled in just 11 days.
- The CDC warned last week that the Delta variant could soon become dominant in the US.
- See more stories on Insider's business page.
As of June 16, the Delta coronavirus variant made up 31% of all coronavirus cases in the US, according to an estimate by the Financial Times.
Previous data from the Centers for Disease Control and Prevention put that rate at about 10% of cases as of June 5, and 2.7% on May 22.
The Financial Times estimate suggests that the share of Delta variant infections in the US tripled in just 11 days.
The CDC has not yet released data on the rate of Delta variant cases after June 5 in the US.
Rochelle Walensky, the head of the CDC, warned last week that the Delta variant could soon become dominant in the US.
And on Sunday, former Food and Drug Administration chief Scott Gottlieb warned that the Delta variant could lead to a surge of cases in the fall if only 75% of eligible Americans are vaccinated by then.
The variant, which was first identified in India and is also called B.1.617.2, appears to be 60% more transmissible than the variant that is now still dominant in the US, the Alpha variant.
Data from the UK, where the Delta variant makes up about 90% of current coronavirus cases, also suggests that the risk of hospitalization is higher for unvaccinated people with this variant.
The Delta variant also appears to more likely to evade the protection given by partial vaccinations.
A single shot of Pfizer or AstraZeneca's COVID-19 vaccines gave just 33% protection against symptomatic COVID-19 cases with the Delta variant, compared to at least 88% for other variants.
However, two doses of the Pfizer or AstraZeneca shot have been found to be protective against hospitalization with the variant.
It is not clear what protection other vaccines give against this variant.
On Friday, President Joe Biden warned that the Delta variant was "particularly dangerous for young people," who are less likely to be vaccinated than older adults and are more socially active.
He also urged all Americans to get a second dose of vaccine.
As of Monday, 45% of Americans are fully vaccinated and 53% have received one dose of vaccine, according todata from the CDC. But vaccination rates have fallen in the last two months.