The CDC is sending monkeypox vaccines to people at high risk in a race to

The Biden administration has distributed 1,200 monkeypox vaccine doses for people who have had high-risk exposures to the virus, part of a nationwide public health response to stamp out the disease before it causes a major outbreak.

U.S. health officials, worried the virus is spreading faster than previously thought, have said the global outbreak of monkeypox is the largest ever. The World Health Organization said Wednesday that there are now more than 550 cases across 30 countries. In the U.S., at least 20 confirmed or suspected cases have been reported in 11 states, including California, Colorado, Florida, Georgia, Illinois, Massachusetts, New York, Pennsylvania, Virginia, Utah and Washington state, according to the Centers for Disease Control and Prevention.

“A monkeypox outbreak of this scale and scope across the world, it has not been seen before,” Dr. Raj Panjabi, who leads the White House pandemic preparedness office, told reporters on a call last week.

However, CDC officials have sought to reassure the public that the arrival of monkeypox in the U.S. is vastly different from Covid-19, which blindsided the country two years ago. Scientists knew little about Covid when it first emerged and the U.S. had no vaccines or antiviral treatments to fight the virus in 2020.

Monkeypox, on the other hand, has been known to scientists since 1958 when the virus was first identified during outbreaks among monkeys kept for research purposes, and its transmission in humans has been studied since the 1970s. Global health authorities also have extensive experience successfully fighting smallpox, which the World Health Organization declared eradicated in 1980 after a successful global vaccination effort. Monkeypox is in the same virus family as smallpox though it is much milder.

Last week, CDC official Dr. Jennifer McQuiston said the U.S. has 1,000 doses of Jynneos available. However, the Danish biotech company that makes the shots, Bavarian Nordic, said the U.S. actually has a supply of more than 1 million Jynneos frozen doses stored in the U.S. and Denmark under an order placed in April 2020. The shots have a shelf life of three years.

The U.S. has ordered close to 30 million Jynneos doses since 2010 but 28 million of them expired, the spokesperson said. Bavarian Nordic plans to increase production this summer and has the capacity to produce 30 million shots a year, the spokesperson said.

The U.S. government also has a stockpile of more than 100 million doses of ACAM2000, made by Emergent BioSolutions, McQuiston told reporters last week. The U.S. had released 500 doses of Jynneos and 200 doses of ACAM2000 as of Tuesday, according to the CDC. The U.S. has also sent out 100 courses of the oral antiviral tecovirimat to the states, health officials said Friday.

“We want to ensure that people with high risk exposures have rapid access to vaccines and if they become sick, can receive appropriate treatment,” Panjabi said on a call with reporters Friday. Jynneos and ACAM2000 can be administered before or after exposure to the virus. However, patients need to receive the vaccines within 4 days of exposure to prevent disease onset.

ACAM2000 has demonstrated high levels of protection against monkeypox in animal models and is expected to provide 85% protection against disease from the virus similar to earlier versions of smallpox vaccines, according to Mike Slifka, an immunologist at Oregon Health and Science University who has studied monkeypox. Less is known about Jynneos because the vaccine is newer but it produced reasonable antibody levels in humans and should protect against severe disease, Slifka said.