A microscope image of the oval-shaped monkeypox virions. [Source: 1 News]

Following the growing number of monkeypox cases, US health officials have expanded vaccine measures, while the EU is investigating whether the US vaccine could be used to combat the spread of the disease within Europe.

In a statement, US officials said they would be providing more monkeypox vaccines, working to expand testing, and taking other steps to try to get ahead of the outbreak.

“We will continue to take aggressive action against this virus,” said White House Covid-19 response coordinator, Dr Ashish Jha.

Case counts have continued to grow in the US. As of Tuesday (local time), 306 cases had been identified in 27 states and the District of Columbia.

The administration said it was expanding the pool of people who are advised to get vaccinated to include men who have recently had sex with men at parties or in other gatherings in cities where monkeypox cases have been identified.

A two-dose vaccine, Jynneos, is approved for monkeypox in the US. So far, the government has deployed over 9,000 doses.

Officials on Tuesday said they are allocating another 56,000 doses immediately and 240,000 more over the coming weeks.

They promised more than 1 million more over the coming months.

In Europe, the vaccine, which is known as Imvanex, is only authorized in adults for the prevention of smallpox.

In a statement on Tuesday, the European Medicines Agency (EMA) said it would begin investigating the use of the vaccine for monkeypox.

“The decision to start this review is based on results from laboratory studies suggesting that the vaccine triggers the production of antibodies that target the monkeypox virus,” the EMA said.

The regulator said that supplies of the vaccine are currently very limited in Europe.

Britain, which has the biggest outbreak beyond Africa, recently widened its vaccination policy to those at the highest risk of monkeypox, which it defined as “gay and bisexual men at higher risk of exposure,” meaning those who have “multiple partners, participate in group sex or attends ‘sex on premises’ venues.”

Britain’s Health Security Agency said there were now 1,076 cases of monkeypox nationwide and they expected to see infections rise further “in the coming days and weeks.”

According to the US Centers for Disease Control and Prevention, there are currently more than 4,300 cases of monkeypox globally, of which the majority are in Europe.