​The highly contagious Delta variant of the SARS-CoV-2 virus now makes up an estimated 83% of new COVID-19 cases in the US, according to the CDC.

Dr. Rochelle Walensky, the director of the CDC, announced the new estimates during a hearing of the Senate Committee on Health, Education, Labor, and Pensions. The new data can now be found on the CDC's website.

Cases of the Delta variant have surged in the US. The variant had accounted for approximately 32% of COVID-19 cases in the US as of June 19 and 62% of cases as of July 3, according to CDC data.

The rise of the variant coincides with a significant increase in coronavirus cases across every state over the last 2 weeks. COVID-19 hospitalizations and deaths are also on the rise, according to the CDC, but new cases, hospitalizations, and deaths are still far lower than they were at their peaks in January and February 2021.

However, the vast majority of new cases, hospitalizations, and deaths are among people who are not vaccinated. Tuesday's hearing before Congress followed a White House briefing last week in which Walensky warned that COVID-19 is “becoming a pandemic of the unvaccinated." Officials at that briefing said that more of 97% of people who are being hospitalized with COVID-19 are unvaccinated, and 99.5% of new deaths are among the unvaccinated.

CDC data show that nearly 60% of adults and nearly 50% of the total population are fully vaccinated in the US, but vaccination rates have slowed since the spring.