Smallpox vaccine Jynneos can prevent monkeypox, CDC says

ATLANTA - The U.S. Centers for Disease Control and Prevention said one of the country’s smallpox vaccines is effective in preventing monkeypox. 

According to the agency, the U.S. currently has ACAM200 and Jynneos, which are both licensed smallpox vaccines. However, JYNNEOS is also licensed specifically to prevent monkeypox.

The Jynneos vaccine is a two-dose vaccine given four weeks apart. People are not considered vaccinated until they get the second dose, according to the CDC. 

FOX Business reported the U.S. has more than 1,000 doses of the two-dose vaccine in the Strategic National Stockpile, according to Capt. Jennifer McQuiston, the deputy director of the CDC's High Consequence Pathogens and Pathology division. Alternatively, there are about 100 million doses of the older smallpox vaccine, ACAM2000. 

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"We expect that level to ramp up very quickly in the coming weeks as the company provides more doses to [the U.S.]," McQuiston said at a media telebriefing. 

Jynneos, made by Bavarian Nordic A/S, has been approved in the U.S. since 2019 for use against smallpox and monkeypox in high-risk adults aged 18 and older.

McQuiston said ACAM2000 potentially has significant side effects and there would have to be some "serious discussion" before it is widely used.

Monkeypox is a virus that originates in wild animals like rodents and primates, and occasionally jumps to people. It belongs to the same virus family as smallpox. 

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Cases are typically limited to Africa, and rare cases in the U.S. and elsewhere are usually linked to travel there. A small number of confirmed or suspected cases have been reported this month in the United Kingdom, Portugal and Spain. U.S. health officials said Monday they knew of one confirmed case, in the state of Massachusetts, and four probable cases — two in Utah, one in Florida and one in New York City. All were men who had traveled outside the U.S.

Health officials are still investigating the latest outbreak, but a top adviser to the World Health Organization said this week that the leading theory is that monkeypox was likely spread after sexual activity at two recent raves in Europe.

Monkeypox typically begins with a flu-like illness and swelling of the lymph nodes, followed by a rash on the face and body. In Africa, people have been infected through bites from rodents or small animals, and it does not usually spread easily among people.

Monkeypox also requires very close contact to spread, so it is not likely to prompt big waves of disease like COVID-19, which can be transmitted in the air by people with no symptoms.

The Associated Press contributed to this report. This story was reported from Los Angeles.