This year, the disease was found in the Sudanese capital for the first time, and Peru recently declared a state of emergency in most regions due to a surge in cases.

The outbreak was first reported this month in Britain – which has registered 111 cases, mostly in children under 10 – and has since been identified in at least 12 countries worldwide.

But they recommend a second booster for people aged 80 and above.

The expected rise in cases is linked to the highly-transmissible Delta variant along with the relaxing of measures in European countries.