LONDON — British health authorities said Friday that the monkeypox outbreak across the country may be peaking and that the growth rate may have slowed.
The Health Security Agency in Britain said there were early signs that the outbreak is plateauing, with 2,859 cases detected since May. There have been no deaths. The outbreak has doubling in size every two weeks, but the number of new infections has dropped in recent weeks, according to authorities.
The growth of the outbreak has slowed, but we can't be complacent, said Dr. Meera Chand, Director of Clinical and Emerging Infections at the Health Security Agency. She said anyone who thought they might have monkeypox should skip social gatherings and avoid sexual contact.
The Health Security Agency said in its most recent analysis of the outbreak that monkeypox is mainly transmitted in intertwined sexual networks of gay, bisexual or men who have sex with other men. More than 70% of the cases in the U.K. are in London.
British officials noted a small number of infections among women, but said there was not enough evidence to suggest that there was a sustained spread of monkeypox beyond gay and bisexual men. 99% of all cases in the U.K. are in men.
Scientists who studied monkeypox viruses in the U.K. noted a number of mutations compared to viruses in Africa, but said there was no evidence that those genetic changes made monkeypox more transmissible.
Experts believe that monkeypox outbreaks in North America and Europe may have originated in Africa long before the disease started spreading via sex at two raves in Spain and Belgium.
The World Health Organization said this week that 92% of monkeypox cases beyond Africa are likely to have been infected through sex, and its Director-General recently appealed to vulnerable gay and bisexual men to reduce their sexual partners for the moment. More than 26,000 monkeypox cases have been reported in nearly 90 countries, with a 19% increase in the last week.
In June of this year, British authorities expanded their vaccination strategy, which includes not only health workers treating monkeypox patients and high-risk contacts of patients, but also to some men who are gay or bisexual and at high risk of contracting the disease, including those with multiple sexual partners or who participate in group sex.
The U.K. downgraded its assessment of the monkeypox outbreak last month and dropped a recommendation for the contacts of monkeypox cases to isolate for three weeks unless they have symptoms. The data shows that only a small number of contacts are stricken by monkeypox and there is no evidence that the disease spreads without close, intimate or sexual contact.
On Thursday, the U.S. declared its outbreak of monkeypox to be a national emergency, but WHO declared it a global emergency last month.
Monkeypox spreads when people contact an infected person's lesions, clothing or bedsheets. Most people recover without needing treatment, but the lesions can be extremely painful and more severe cases can cause serious complications, including encephalitis and death.