We thought measles was history. The data shows that we were very wrong

For years, measles seemed like a disease of the past in much of the developed world thanks to mass vaccination campaigns who had managed to corner the virus until turning the outbreaks into anecdotes. However, everything is changing as the WHO itself points out either the US CDC by drawing a very different scenario: measles has returned and it has done so with unusual force.

The return What began as an “immunity gap” after the pandemic has become in a worrying statistical trend. From the Mediterranean to the United States, and with an echo in Spain, the figures for 2024 and what we have for 2025 confirm a global rebound that tests herd immunity.

The global ‘leap’. To understand the magnitude of the problem, you have to look at the raw numbers that the WHO itself offers ussince it makes us see that we are not facing a standard seasonal rebound, but rather it is a very important change in trend. In this case the European Region The WHO has registered 127,350 cases in 2024, a figure that not only doubles the records of 2023, but also marks the all-time high since 1997.

In depth. If we break them down, we can see that in Europe cases have increased by 47% compared to pre-pandemic levels and in the Eastern Mediterranean the increase is 86% compared to 2019. In the case of the European Union, ECDC documents more than 35,000 cases in 2024, which increases ten times the previous year.

The severity lies not only in the contagion, but in the consequences: more than half of these cases in Europe have required hospitalization. And this leads to greater pressure on care.

In the United States. If in Europe there is a lot of concern about this issue, in the North American country, since the growth is vertical. The CDC itself has set off alarms after observing how cases have multiplied by five in a matter of months. In this way, while approximately between 285 and 300 cases were reported in all of 2024, projections and partial data for 2025 place the figure above 1,500 affected.

This paints a very clear picture: 92% of infections occur among people who have not been vaccinated, with outbreaks concentrating in communities with low immunization.

The case of Spain. If we focus on our country The truth is that we have remained free of endemic measles since 2017. This means that the virus does not constantly circulate freely within our borders. However, globalization is causing a change in photography.

Official data indicates that while in 2023 only 14 cases were recorded, in 2204 they increased to 229 cases and in 2025 the forecast points to almost 400.

Its origin. The Ministry of Health and the Spanish Association of Pediatrics (AEP) point out that the majority are imported cases (mainly from Morocco and Romania) that find “small gaps” to spread. Although there are active outbreaks in communities such as Andalusia, the Basque Country and Catalonia, the virus enters from outside and lights the fuse in non-immunized groups.

The mathematics. Measles is one of the most contagious viruses that exists, and to keep it at bay through herd immunity, the WHO establishes a fairly strict safety threshold: 95% of the population must have both doses of the vaccine. This is something where Spain is doing quite well, since the first dose has a coverage of 96-97%, while the second drops to 91-93%.

But this difference between having one or two doses is very important. That margin of two or three percentage points below the recommended 95%, added to the anti-vaccine movements and delays in post-COVID vaccination, is the crack through which the virus is sneaking in. Although the general population is protected, there are enough “pockets” of vulnerable population for an imported case to generate a local outbreak.

Images | Wikipedia Fusion Medical Animation

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