▶ Watch Video: U.S. officials prepare to release monkeypox vaccines as more cases emerge

The U.S. is facing at least two separate outbreaks of monkeypox, federal health officials said Friday, based on samples of virus that have been genetically sequenced from some cases so far. 

A CDC official said the sequenced monkeypox cases — which now include patients in Massachusetts, Florida, Virginia and Utah — suggest the majority of cases spotted in the U.S. are linked to the variant that has been spreading in Europe. Those also appear similar to the virus spotted in an infected traveler to Maryland from Nigeria last year.

However, at least two of the U.S. cases do not appear to be closely linked to the virus spreading in Europe. Instead, they look similar to a virus sample from a traveler to Texas last year. 

“It’s not clear what all this means, but it’s likely that within the last couple of years, there have been at least two different instances where monkeypox virus spilled over to people in Nigeria, from the animal that maintains it,” Jennifer McQuiston, head of the CDC’s monkeypox response, told reporters at a briefing on Friday. 

“That virus likely began to spread through person-to-person close contact, possibly intimate or sexual contact,” McQuiston added. 

The CDC’s finding comes as both the domestic and global tally of monkeypox cases has climbed sharply over the past few weeks, amid a push from health authorities to find and test potential cases of the at-times painful rash and lesions.  

The majority of cases, but not all, have been in men who have sex with men with links to recent travel abroad. However, McQuiston said Friday that at least one U.S. case “does not have a travel link or know how they acquired their infection.” 

“It’s possible there could have been other cases in travelers that were missed, but I don’t think that monkeypox has been circulating widely within the United States,” she said.

A total of at least 23 cases have been tallied so far by health authorities across the U.S., including one case in a Florida resident who was tested in the United Kingdom. California, Colorado, Florida, Georgia, Hawaii, Illinois, Massachusetts, New York, Pennsylvania, Utah, Virginia and Washington state have reported at least one case.

The CDC is also aware of more than 700 confirmed cases around the world. 

“I actually think the finding of these two cases with distinct lineages is actually a positive sign that our surveillance network that we’re working to increase, and make sure that people with a rash get tested, is working,” McQuiston added.

No deaths have been reported in the U.S. so far. Authorities say they believe the risk to the general public is low, since the virus is generally spread through intimate skin-to-skin contact. 

However, officials emphasized they did not want to minimize the monkeypox’s threat to those who might catch or spread the disease.

“The rash caused by monkeypox virus can spread widely across the body or present in sensitive areas like the genitalia. It can be really painful and some patients have reported needing prescription pain medicine to manage that pain. The sores can also cause long term scarring on the skin,” said McQuiston. 

The CDC recently issued warnings for travelers to take precautions to avoid catching monkeypox, including to wear a mask and avoid contact with things like wild game meat and contaminated clothing.

McQuiston said the CDC is also mulling launching a new health alert and other outreach to medical providers to raise awareness around the outbreak to help spot cases, including on the possibility that patients could be co-infected with monkeypox and other diseases.

Out of more than 400 close contacts of the U.S. cases so far, authorities have identified at least 56 who are considered high-risk contacts.

That figure is from a report also published Friday in the CDC’s Morbidity and Mortality Weekly Report, documenting the response to the first 17 U.S. cases of monkeypox. 

While the first case in the current outbreak tested positive for monkeypox on May 18, the report reveals that the earliest U.S. case spotted in Massachusetts developed their symptoms on May 4. They were later hospitalized on May 12, due to pain from their rash. 

Some at-risk providers who came into contact with the hospitalized person were later offered vaccine, in hopes of heading off potential infections.

“We want to ensure that people with high-risk exposures have rapid access to vaccines, and, if they become sick, can receive appropriate treatment,” Dr. Raj Panjabi, the White House’s senior director for global health security and biodefense, told reporters. 

Panjabi said that the Biden administration has deployed some 1,200 doses of vaccine and 100 treatment courses to at-risk contacts and patients in the outbreak. Most have been of the recently-approved Jynneos vaccine, produced by Bavarian Nordic, which several states say they have sought out from the federal government’s stockpile. 

Officials said U.S. stockpiles of Jynneos have climbed, but declined to offer a specific figure citing “national security.” 

“We continue to have more than enough vaccine available. We do have them pre-positioned in several sites around the country,” Dawn O’Connell, assistant secretary for preparedness and response at the Department of Health and Human Services, told reporters. 

O’Connell’s agency oversees the national stockpile of both Jynneos and the older ACAM2000 vaccines, which have also been requested by at least one state. 

O’Connell said authorities had been cautious about shipping too many doses of Jynneos out of Bavarian Nordic’s cold storage, which shortens the shelf life of the vaccines.

“We’re working closely with Bavarian Nordic to make sure that we’re pre-positioning the vaccine that we think we currently need,” said O’Connell.