Notices of measures against COVID-19 are seen on a door of a store in New York, the United States, Feb. 14, 2022.(Xinhua/Wang Ying)

Experts warned that the United States may see another rise in COVID-19 cases in the next few weeks as the new Omicron subvariant continues to spread across the country.

Infections of the the highly transmissible variant, known as BA.2, have been doubling each week, according to data of the U.S. Centers for Disease Control and Prevention (CDC).

As of the week ending March 12, BA.2 makes up 23.1 percent of all COVID-19 cases in the country, compared to 1 percent of new cases in the week ending Feb. 5, and 7.1 percent in the week ending Feb. 26, CDC data showed.

Although the original Omicron variant still makes up the majority of COVID-19 infections in the country, its prevalence has dropped to 66.1 percent in the week ending March 12.

Anthony Fauci, the nation's top infectious disease expert, said he expects "an uptick in cases" due to BA.2, but not necessarily a massive surge like other variants have caused.

Fauci told ABC on Sunday the new strain is about 50 to 60 percent more transmissible than the first Omicron strain, adding that it could take over as the dominant strain in the United States.

However, he noted that the strain does not appear to cause more severe illness or evade immune responses from vaccination or prior infection.

U.S. Surgeon General Vivek Murthy also said the variant could cause a new spike in cases, but adding that the country is in a better position now than it was in the previous two years.

Several European countries, such as Finland, France, Germany, the Netherlands and the United Kingdom, have reported a spike in COVID-19 cases over the last couple of weeks.

Health officials continue to stress COVID-19 vaccines and boosters remain the best ways to prevent serious illness from the virus.

According to CDC data, 76.7 percent of the total U.S. population has received at least one dose of a COVID-19 vaccine, and 65.3 percent has completed their primary series as of March 16. However, only about half of the booster-eligible population has received a booster dose.