Monkeypox continues to spread across the United States, but the pace of new cases has slowed in recent weeks, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, told lawmakers on Wednesday.

While the virus is still spreading rapidly in certain regions of the U.S., the rise in new monkeypox cases across the country and globally has slowed in recent weeks, she told the Senate Committee on Health, Education, Labor and Pensions Wednesday.

“We approach this news with cautious optimism,” she said at a hearing.

The US is working to contain the world’s largest monkeypox outbreak, with more than 22,600 cases in all 50 states, Washington DC and Puerto Rico, according to CDC data.

The disease is rarely fatal but causes painful lesions that resemble pimples or blisters. According to Walensky, there has been one confirmed death in the United States as a result of the disease.

The Jynneos vaccine, manufactured by Danish biotech company Bavarian Nordic, is the only approved monkeypox vaccine in the United States. Two doses are given 28 days apart, and CDC officials say getting the second shot is crucial for those at risk. After the second dose, it takes two weeks for the immune system to reach its maximum response.

People with monkeypox should stay home until the rash has healed and a new layer of skin has formed, maintain a safe distance from other people, and not share objects or materials with others, CDC guidelines say.

CNBC Health & Science

Read CNBC’s latest global health coverage: