Measles cases across the world rose by 88 percent between 2022 and 2023, almost doubling from 171,153 to 321,582 cases. According to the figures, presented at a recent conference, 2024 looks set to be just as bad, sparking calls from health officials for new strategies to maximize vaccine coverage around the globe.

Humanity has been contending with measles for centuries, and it’s among the most contagious diseases threatening our species. When the first effective vaccine hit the market in the 1960s, followed less than 10 years later in the US by the combined measles, mumps, and rubella (MMR) vaccine, eradicating a disease that killed approximately 2 million people every year looked like a real possibility for the first time.

For complete coverage, it’s recommended that all children receive at least two doses of a measles vaccine. Age recommendations vary by region and according to a child’s risk of exposure; in the UK, for example, the National Health Service recommends all children receive their first MMR vaccine when they’re 1 year old, and the second before they start school at age 5.

“The measles virus is extremely infectious and any gaps in immunisation coverage are potential risk for outbreak. So, coverage needs to high but also uniform and equitable,” explained Dr Patrick O’Connor of the World Health Organization (WHO) in a statement.

While Dr O’Connor and co-presenter Professor Hanna Nohynek, of the Finnish Institute for Health and Welfare, acknowledge that incredible progress has been made this century, the new data do present cause for some alarm.

As well as the overall increase in cases, the period between December 2022 and November 2023 saw a tripling of the number of countries experiencing large measles outbreaks, defined as a continuous 20 cases per million of the population.

“Measles cases were high in 2019, with the majority seen in Africa,” said Professor Nohynek. This continent, she explained, has historically seen the lowest vaccine coverage and has suffered regular measles outbreaks.

An early look at the 2024 data, however, throws the spotlight on another area: the WHO European Region. Of the cases so far recorded this year, 45 percent have occurred in this region, which covers 53 countries. Three of these – Yemen, Azerbaijan, and Kyrgyzstan – currently have the highest reported measles incidences in the world.  

A specific review of measles elimination in the European Region will take place in September this year, Dr O’Connor explained. But in the meantime, both experts stressed the need for innovative ways to boost vaccination coverage, for all children, everywhere.

“During the [COVID-19] pandemic, many children remained unvaccinated, and catchup vaccinations have not reached them. Therefore we now see cases increasing again in various regions of the world,” said Professor Nohynek.

Vaccine hesitancy is also a longstanding problem, and it arguably affects measles vaccines more than most. Memories of the scaremongering around the MMR and purported links to autism, based on fraudulent science that has been thoroughly and repeatedly debunked, live long in the mind – and sadly, on the internet.

This year, UK officials declared a national incident after a sharp increase in measles cases; in total, 41 member states of the WHO European Region reported cases in 2023. There are even concerns that the United States’ measles elimination status may be under threat.

Encouraging vaccine-hesitant parents is only part of the picture, as Professor Nohynek explained: “Vaccine hesitancy is only one component that can contribute to lower coverage – misinformation about vaccines, access to immunization services, and on-time vaccination cause immunization gaps.”

It means that we likely need lots of different strategies to tackle these different aspects simultaneously. Professor Nohynek pointed to new innovations in vaccine delivery, like the needle-free measles-rubella microarray patch, as well as countries using disease surveillance to identify and plug gaps in vaccine coverage.

“Over the last 20 years,” Dr O’Connor concluded, “there has been significant progress toward achieving measles and rubella elimination – in order to solidify and maintain those gains, we need to ensure high, uniform and equitable routine immunization coverage; and robust outreach and rapid outbreak response.”

The data were presented at the 2024 ESCMID Global Congress.