It's still too early for doctors to know just how transmissible and contagious the new variant may be, but doctors are warning not let your guard down.

"We're not sure yet how bad it's going to be," said Dr. Mangala Narasimhan, of Northwell Health. He says it's too soon to tell just how severely we'll be impacted. "There's a lot of mixed reports coming out of South Africa as to how virulent it is and how sick people get," he said.

Doctors also cannot say for certain yet whether the omicron variant is more dangerous than previous versions of COVID-19. So far, it has been reported in about one-third of states, including at least eight cases in New York.

"My level of concern is high. I'm concerned that it's very transmissible," said Narasimhan.

The variant prompted federal health officials to issue new travel restrictions across the country. Beginning Monday, travelers flying to the U.S. are required to show proof of a negative test within one day of boarding their flight.

President Joe Biden has also extended the federal rule requiring passengers on mass transit to wear masks through at least March. That includes the Long Island Rail Road, New York City subways and Metro-North trains.

While the omicron variant may be dominating the COVID-19 conversation right now, health officials say the delta variant is still the cause of 99% of current cases.

"The hospitals on Long Island are unfortunately extremely busy, we have a lot of COVID, a lot more than we had a month ago," said Narasimhan. "People are sick, just like they were a year ago, people who are not vaccinated are really the ones that we're seeing in the ICUs."

Doctors are urging people to get vaccinated, get their booster shots and wear masks to protect themselves from all forms of the coronavirus.