A spate of breakthrough mpox infections in fully vaccinated patients suggests that vaccine-induced immunity does not offer complete protection against infection, doctors warn.

Repeat infections have also occurred, pointing to waning natural immunity against the mpox virus, say authors of two separate case series covering 39 men who have sex with men (MSM).

But they said these cases were clinically less severe and had reduced disease duration compared with those seen in the 2022 outbreak, with most only requiring conservative management, such as OTC analgesia.

In the first case series, Australian doctors reported on two breakthrough infections in patients fully vaccinated with the third-generation JYNNEOS modified vaccinia vaccine.