By David García Pérez
This article is translated from from Univadis Germany, part of the Medscape Professional Network. Pérez has previously written about the Oropouche virus, Ascariasis medication, and anthelmintic medications for Medscape.
September 9, 2026
Two Pennsylvania residents died after contracting measles, drawing renewed attention to a disease that the US declared eliminated. The deaths occurred amid an increase in cases, with more than 2777 measles cases confirmed in the US to date.
The increase is particularly striking because only three measles deaths were recorded in the US between 2001 and 2022, with the most recent occurring in 2015. The CDC subsequently confirmed three deaths in 2025.
The resurgence in the US is part of a broader phenomenon affecting other countries with well-established healthcare systems and raises an important question: Why are diseases that have been controlled for decades reappearing?
For decades, diseases including measles, diphtheria, and polio have ceased to be everyday threats in many high-income countries because of vaccination. However, some of these pathogens have once again found opportunities to spread.
In Europe, 127,350 measles cases were reported in 2024, twice the number reported in the previous year and the highest number recorded in the region since 1997. In addition, 38 deaths were reported. Although the number of cases fell to 33,998 in 2025, the World Health Organization (WHO) and United Nations Children’s Fund (UNICEF) warned that the risk for new outbreaks would persist because of pockets of insufficiently vaccinated populations.
Italy offers a particularly striking example of how diseases that once seemed relegated to the past could become fatal.
Recently, an unvaccinated 4-year-old girl died of respiratory diphtheria in Palermo, Italy.
The diagnosis was later confirmed by the Italian National Institute of Health. The case occurred in an EU setting where diphtheria continues to be reported despite vaccination.
In 2024, 151 cases were reported in the EU and European Economic Area, including 83 caused by toxigenic Corynebacterium diphtheriae and 65 caused by Corynebacterium ulcerans.
Nor is the problem limited to measles or diphtheria. In 2022, the US reported a case of paralytic polio in an unvaccinated adult in New York, the first detected in the country since 2013. The individual was infected with a type 2 vaccine-derived poliovirus (VDPV2), and viruses genetically related to the individual’s isolate were subsequently identified in wastewater from several counties, providing evidence of community transmission.
Germany subsequently reported to the European Centre for Disease Prevention and Control (ECDC) the detection of wild poliovirus type 1 in a wastewater sample from Hamburg, Germany, although no associated human cases had been identified.
The detection followed reports from several EU countries, including Finland, Germany, Poland, and Spain, which had detected VDPVs in wastewater in 2024. These findings prompted the ECDC to call for increased vaccination and surveillance.
The resurgence of these pathogens does not mean that vaccines have stopped functioning. Instead, it highlights a fundamental issue: When vaccination coverage declines, the number of susceptible individuals increases. These cases therefore raise a broader question: What is happening with vaccination in societies that have managed to keep these diseases at bay for decades?
Recent Data
Childhood vaccination has transformed global health and prevented millions of deaths; however, progress in vaccination coverage has slowed over the past decade.
A recent analysis published in The Lancet examined the coverage of 11 vaccine combinations across 204 countries and territories from 1980 through 2023. The analysis estimated that routine vaccination has prevented approximately 154 million child deaths since 1974. However, progress has stalled in many areas since 2010, and the coverage of at least one recommended vaccine has declined in 21 of the 36 high-income countries analyzed.
This decline was not limited to a single vaccine. According to the same study, the coverage of the first measles vaccine dose decreased between 2010 and 2023 in 100 of the 204 countries studied. Among high-income countries, declines occurred in France, Italy, Japan, the UK, and the US. The COVID pandemic worsened a trend that had already shown signs of stagnation. Disruptions to healthcare services and immunization programs have led to losses in coverage that have not recovered uniformly.
The latest WHO and UNICEF data show that coverage has declined in some countries, while remaining stable or recovering in others. Therefore, a generalized decline in vaccination across all high-income countries cannot be assumed.
However, why is this happening? The answer is more complex than a single cause. The Lancet analysis identified health inequalities, consequences of the pandemic, and stagnation in immunization programs as major barriers to vaccination coverage. Another increasingly important factor is confidence in vaccines.
Misinformation and vaccine hesitancy can reduce vaccine acceptance, particularly when diseases prevented by vaccination are no longer perceived as daily threats. However, not every unvaccinated individual is hesitant to be vaccinated.
Difficulties in accessing healthcare, lack of information, problems completing vaccination schedules, and social inequalities may also account for some coverage gaps.
The future will depend to a large extent on which of these trends prevails. The study’s projections estimated that if the current trajectory continues, global coverage of the second measles vaccine dose will reach approximately 76% by 2030, well below the international target of 90%. In a more favorable scenario, the coverage could exceed 85%, whereas in an unfavorable scenario, it could be below 63%. These figures serve as a warning: Maintaining vaccination coverage requires not only making vaccines available but also ensuring that they reach the entire population and that individuals have confidence in them.
Restoring Lost Protection
Given this situation, restoring vaccination coverage is not simply a matter of compensating for doses that were missed during the pandemic. In Europe, current strategies also seek to identify where pockets of unvaccinated populations are concentrated and which barriers prevent some individuals from accessing or accepting vaccination.
The ECDC estimated that approximately 600,000 children aged 12-23 months may not have received at least one recommended childhood vaccine in Europe and has developed tools to help health authorities improve vaccination acceptance and coverage.
One strategy involves catch-up vaccination, which allows individuals who were not vaccinated at the recommended time to complete their vaccination dose. These interventions are combined with better identification of susceptible individuals and measures targeted specifically at communities where vaccination coverage is the lowest.
In Romania, for example, certain regions have increased measles, mumps, and rubella vaccination coverage by 25% during the first quarter of 2026, after implementing measures aimed at reversing the decline in vaccination rates.
The WHO and UNICEF have warned that, in Europe and Central Asia, coverage for several childhood vaccines has stagnated or declined compared with pre-pandemic levels.
The goal, therefore, should not simply be to return to pre-pandemic levels but to ensure that immunity gaps continue to narrow and that vaccination systems can quickly detect and address any decline in coverage. Vaccination is one of the most effective public health interventions. The challenge is to ensure that these tools reach all communities and that coverage remains high enough to prevent vaccine-preventable diseases from gaining a foothold and spreading.
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