The WHO said in a statement that it gave the Jynneos vaccine prequalification for adolescents on October 8.
The WHO declared mpox a global public health emergency for the second time in two years in August after a new type of the virus spread from the Democratic Republic of Congo to its neighbours.
The United Nations agency approved the use of the vaccine in September as the first shot against mpox in adults, making it easier for badly hit African countries to access the vaccine.
Children, adolescents and those with weakened immune systems have been particularly vulnerable to mpox, a viral infection that typically causes flu-like symptoms and skin lesions filled with pus.
WHO's latest decision comes after the EU approved the drug for the vaccine for adolescents in September.
The Danish biotech firm is also preparing to conduct a clinical trial to assess the vaccine's safety in children aged two to 12, potentially extending its use.
The trial, partially funded by the Coalition for Epidemic Preparedness Innovations, is expected to start in October.
The US Food and Drug Administration has also approved Bavarian's shot, but only for use in adults 18 years and older, although it granted Emergency Use Authorisation for its use in adolescents during the mpox outbreak of 2022.
Another mpox vaccine, LC16, made by Japan's KM Biologics, can already be given to children, according to the Japanese regulator, although it requires a special kind of needle.
