Startling figures released by the World Health Organization (WHO) on Monday showed the extent to which measles has overrun the globe in the last few months.

The data show that the number of cases of measles worldwide more than trebled in the first three months of 2019, compared to the same period in 2018, increasing from around 28,000 to 112,000 cases.

WHO is clear that stagnating vaccination rates are one of the key reasons behind the disease's resurgence.

At least 95 per cent of people need to be vaccinated against measles to stop it spreading, to achieve what is known as "herd immunity". However, from the end of 2017 just 67 per cent of people globally had received the recommended two doses of the vaccine, with coverage rates pitifully low in many places.

Yet even places with high overall coverage rates are not immune to outbreaks. With highly infectious diseases like measles, it only takes a few pockets of poor coverage within a country or a city for an outbreak to happen.

Reasons for inadequate immunisation rates vary. Some children, particularly in poor or conflict-affected countries miss out on vaccines because they do not have access to good quality healthcare. However, others are not immunised due to their parents’ eschewal of vaccines.