The delta variant continues to spread through the country and accounts for 83% of genetically sequenced COVID-19 cases in the U.S.

Doctors say the age group with the lowest vaccination rate is kids ages 12 to 15. Pfizer and Moderna are still doing clinical trials. There's also talk of whether the mask mandate should be reinstated.

Dr. Jurate Ivanaviciene, an infectious disease specialist from Hartford Health Care Saint-Vincent's Medical Center, says now that it is in the U.S., it will make its way to places like Connecticut. She urges people to get vaccinated and explains how the data proves it is effective.

Dr. Chris Hahn, an emergency medicine physician at Mount Sinai Morningside, says the concern is how transmissible the variant is.

"It is basically twice as contagious as the original variant that we had circulating last year," says Hahn.

The Olympics haven't even started but there are more than 70 cases linked to officials and athletes even though they were vaccinated.

Hahn says it is extremely rare to get severe disease and end up in the hospital. The breakthrough cases are rare and shouldn't discourage people from getting vaccinated.

All of the pharmaceutical giants are looking into whether or not people will need booster shots.