The CDC says the delta variant of COVID-19 is as contagious as chickenpox, and those who are vaccinated could still spread it and it could lead to more severe disease.

"You don't screw around with this virus," said Dr. Jonathan Reiner, a CNN medical analyst. "This variant can kill you. It's much more contagious than the common cold. It's about as contagious as chickenpox, which is a very contagious virus."

Medical experts are saying the delta variant causes more severe illness than earlier variants.

Vaccinated people tend to have less severe symptoms than unvaccinated people; however, the new data shows vaccinated people can still spread the virus easily.

That's why the CDC announced its recommendation earlier this week for everyone, including those who are vaccinated, to wear masks indoors in places where the delta variant is causing a surge in cases.

The recommendation comes as President Joe Biden is announcing all federal workers either have to get vaccinated or agree to regular COVID-19 testing. Those who are not vaccinated will also have to wear a mask on the job.

The federal government is one of the largest employers in the nation, and Biden is hoping private companies and businesses will follow suit. He announced small and medium-sized businesses will be reimbursed for offering paid time off so employees can get family members vaccinated.

Biden is also directing the U.S. Department of Defense to consider vaccine requirements for members of the military.

“We all want our lives to get back to normal. And fully vaccinated workplaces will - will make that happen more quickly and more successfully,” said the president.

Biden is also calling on state and local governments to use their American Rescue Plan funding to offer incentives of $100 to those who get a vaccination. He also wants school districts all over the country to host at least one pop-up clinic over the coming weeks.