The 500,000 new doses will significantly increase stocks held in the United States, which now likely contain approximately 70,000 doses.
The vaccine will be manufactured using U.S.-owned bulk materials and stored at the drug manufacturer, the announcement said.
And more doses are on the way in the next few years. U.S.-owned bulk materials will be processed into 13 million lyophilized doses from 2023 to 2025.
The CDC has reported 45 cases of monkeypox in 16 states, but officials fear the outbreak may continue to grow as in other countries. Several European countries have reported over 100 cases. The global case count, outside of endemic countries, is now over 1,300.
The US order comes because the vaccine is in short supply in many countries and as several nations partner with Bavarian Nordic to contract for more vaccines.
So many governments have ordered doses that Bavarian Nordic improved its financial outlook for the year in the announcement made on the US order. The Danish company was forecasting revenues of between 1.4 and 1.6 billion Danish kroner and now expects between 1.8 and 2 billion kroner.
And those numbers could continue to grow as the European Union tries to finalize a vaccine deal.
Although health officials noted that monkeypox does not require mass vaccination, those exposed or at high risk of exposure would need the injection, and the increase in the number of cases has significantly increased the demand.
The United States has large stocks of old smallpox vaccines, but the newly ordered vaccines have been deemed safer and much preferred, leading countries around the world to order.
It also led WHO to ask countries to report their stocks and consider sharing doses with countries as needed, something the US has not yet made a public decision on.
Other countries have reported stocking up on some doses and ordering with Bavarian Nordic, but none have announced a number of doses nearly as large as the United States, a figure that is likely to grow over the next few years.