The Centers for Disease Control and Prevention announced new recommendations that vaccinated people return to wearing masks indoors in parts of the U.S. where the coronavirus is surging.

The CDC says the delta variant is responsible for about eight out of 10 new cases.

Dr. Ugo Ezenkwele, chief of emergency medicine at Mount Sinai in Queens, says it's very contagious so we need to protect ourselves and others.

The agency also recommends that everyone in K-12 wear a mask regardless of whether they have gotten a COVID-19 vaccine.

Dr. Ezenkwele says now is the time for the guidance to change. He says we have to follow the science and if putting masks back on will keep people safe than it has to be done.

"I know it's disheartening. It feels like we are almost going backwards but we have to understand that where we are now relative to where we were a few weeks ago or even a few months is alarming," says Ezenkwele.

Former CDC director Tom Frieden says the U.S. could see a big increase in COVID-19 cases over the next month and a half due to the delta variant.

Dr. Frank Illuzzi, medical director of specialty services at Hartford Health Care Fairfield, says it seems that with the delta variant even though people are vaccinated they can still spread it and that's different from the other strain.

Illuzzi says testing is also going to become very important again with the rise in cases.

He says people who work in high-risk jobs should still wear a mask because you don't know who is vaccinated and who isn't.

Illuzzi says we still need to be cautious so that we don't end up where we were last year.

"The more people who get vaccinated the better control we have," says Illuzzi.

Areas like New York City are now mandating that all city workers get vaccinated, or they must wear a mask and get tested weekly.