Declining vaccination rates are raising the risk of resurgence for infectious diseases long held in check, including measles, polio, pertussis, and diphtheria, health officials warn.
The World Health Organization (WHO) reinstated the United Kingdom to the list of countries where measles is endemic in January 2026.
Rising Risk of Outbreaks: What’s Driving the Trend?
According to information obtained by The Telegraph, 3,268 measles cases and two deaths were recorded in England and Wales in 2025. This followed an increase of 11,162 cases in 2024.
Experts attribute the increased risk of outbreaks to falling below the 95% immunization threshold needed for measles vaccine coverage. In England, only 83.7% of children had received two doses of the measles, mumps, and rubella (MMR) vaccine by age five – the lowest level in a decade. This decline in vaccination rates is a significant public health concern, as it leaves communities vulnerable to preventable diseases.
‘Future Cycles of Outbreaks Likely’
“If vaccination rates continue to fall, we are likely to notice recurrent cycles of outbreaks in the future,” said Professor Sir Andrew Pollard, Director of the Oxford Vaccine Group, in a report. The UK Health Security Agency (UKHSA) data shows that one person with measles can infect an average of 15 others. Approximately one in five cases requires hospitalization, and brain inflammation develops in one in 1,000 to 2,000 cases.
Warning About Pertussis and Polio
Experts as well note that the rise in measles cases poses a risk for other vaccine-preventable diseases, such as pertussis (whooping cough) and polio.
In the first half of 2025, 502 laboratory-confirmed cases of pertussis were identified, and one child died. Vaccination rates for pertussis are also concerning, with 82.7% of children in England completing their pertussis vaccinations by age five. Among pregnant women, the vaccination rate is 72.6%.
Polio was last seen in the UK in 1984 and was eradicated in Europe in 2003. However, poliovirus has been detected in sewage samples in England since 2022. Experts warn that low vaccination rates could increase the risk of the virus re-emerging. Currently, 82.7% of children in the UK have completed both doses of the polio vaccine, but in some regions, this rate falls to 60%.
Increase in Diphtheria Cases
Diphtheria, which caused tens of thousands of cases and thousands of deaths in the 1940s, was largely controlled through mass vaccination. However, the annual number of cases has fluctuated between two and ten in recent years, with two cases recorded in 2025.
Dr. Ben Kasstan-Dabush, from the London School of Hygiene & Tropical Medicine, noted that anti-vaccination sentiment and increasing social inequalities are negatively impacting vaccination rates. Experts also point to challenges in accessing healthcare and increased hesitancy following the pandemic as contributing factors.
According to The Telegraph, officials are urging increased vaccination rates and completion of missed doses, warning, “We do not want to see preventable diseases return.”
