A single dose of the monkeypox vaccine provides 78 percent protection against the virus, according to data released in England on Tuesday, which health officials said was the strongest evidence of its effectiveness.
Cases of monkeypox have remained low, but the World Health Organization continues to classify the disease as a global health emergency, its highest level of alert.
The new analysis reviewed Bavarian Nordic vaccine data in England between July 4 and Nov. 3, the UK Health Safety Agency (UKHSA) said.
The single vaccine provides 78% protection 14 days after being given, while a second dose is expected to offer greater and longer-lasting protection, the UKHSA added.
More than 55,000 doses of the vaccine have been administered to date, according to the agency.
Monkeypox, a relatively mild viral disease that is endemic in several countries in West and Central Africa, spread around the world earlier this year.
Since then, there have been more than 80,000 cases worldwide, according to the U.S. Centers for Disease Control and Prevention.