Originally Published: 13 APR 22 11:19 ET

Updated: 13 APR 22 11:42 ET

By Brenda Goodman and Betsy Klein, CNN

(CNN) -- The US Centers for Disease Control and Prevention plans to extend the federal transportation mask mandate for another 15 days to early May, according to a Biden administration official familiar with the decision.

The announcement is expected as early as Wednesday afternoon from the CDC. The mandate is now set to expire on May 3. The Associated Press was first to report the extension.

The administration official familiar with the decision told CNN the goal of the extension was to gather more information and understanding of the BA.2 variant of the coronavirus.

"Since early April, there have been increases in the 7-day moving average of cases in the US. In order to assess the potential impact, the rise of cases has on severe disease, including hospitalizations and deaths, and health care system capacity, CDC is recommending that TSA extend the security directive to enforce mask use on public transportation and transportation hubs for 15 days, through May 3, 2022," the official told CNN.

The official added, "This will give additional time for the CDC to learn more about BA.2 and make a best-informed decision."

The US is now averaging 38,345 new Covid-19 cases per day, according to data from Johns Hopkins University. Cases are trending up in more than half of states -- including all but one state in the Northeast, Delaware. But the daily rate is still one of the lowest since mid-July.

According to the latest estimates from the CDC, BA.2 caused 86% of new Covid-19 cases nationwide last week.

The mandate, which requires masks on public transportation such as planes, trains, buses -- as well as in hubs like airports and bus terminals -- had been set to expire on April 18. White House Covid-19 Response Coordinator Dr. Ashish Jha told CNN on Monday that the CDC planned to share a scientific framework this week for the federal transportation mask mandate.

This is a breaking story and will be updated.