Measles is a highly contagious viral infection that has re-emerged as a public health concern in the United Kingdom despite decades of successful vaccination campaigns. While often perceived as a disease of the past, recent outbreaks emphasise the importance of sustained vigilance, particularly as the UK grapples with shifting public attitudes towards vaccination and the added stressors of climate change and summer heat.
What Is Measles?
Measles is an infectious disease caused by the measles virus. It primarily affects children but can infect individuals of any age who are not immune. The illness typically begins with symptoms such as fever, cough, conjunctivitis (red eyes), and coryza (runny nose), followed by a characteristic red, blotchy rash that usually spreads from the face downwards. It is not merely a benign childhood disease; complications such as pneumonia, encephalitis (brain inflammation), blindness, and even death can occur, particularly in vulnerable groups like infants, pregnant women, and immunocompromised individuals.
Causes and How It Spreads
Measles is caused by the measles virus, which spreads primarily through respiratory droplets when an infected person coughs or sneezes. The virus can remain viable in the air or on surfaces for up to two hours. One of the defining characteristics of measles is its high transmissibility. It is estimated that 90% of non-immune individuals in close contact with a measles patient will become infected.
Infected individuals are contagious from about four days before the rash appears to four days after. This presymptomatic infectious phase complicates containment efforts, especially in densely populated or communal settings like schools, nurseries, airports, and public events.
Measles in the UK
The UK was declared measles-free by the World Health Organisation (WHO) in 2017, but lost this status in 2019 due to declining immunisation rates. This trend has worsened post-COVID-19. According to UK Health Security Agency (UKHSA) data from early 2024, the country experienced a sharp rise in measles cases: over 1,200 confirmed cases in the first half of the year alone, compared to fewer than 300 during the same period in 2023. The hardest-hit areas include London, the West Midlands, and parts of Yorkshire, reflecting both urban population density and disparities in vaccination uptake.
Notably, the MMR (Measles, Mumps, Rubella) vaccine uptake has fallen below the critical threshold of 95%, which is required to maintain herd immunity. In some London boroughs, first-dose uptake among five-year-olds has dropped to as low as 70%, a concerning figure that leaves large pockets of the population vulnerable to outbreaks.
The Role of Summer Heat and Seasonal Dynamics
Measles transmission is not directly tied to weather conditions in the same way that diseases like influenza are linked to colder months. However, summer does introduce unique challenges. As people gather in large crowds at festivals, holiday resorts, airports, and international events, there is increased opportunity for viral spread, especially in areas with low vaccination coverage.
Moreover, high summer temperatures can exacerbate the dehydration and fever associated with measles, particularly in children. This raises the risk of hospitalisation, especially if there is inadequate fluid intake or poor home care. Those suffering from measles during a heatwave may also experience worse outcomes if symptoms are misattributed to heat exhaustion, delaying timely diagnosis and treatment.
Additionally, global travel during summer holidays increases the risk of importing measles from countries experiencing outbreaks, such as Romania, Nigeria, or parts of Southeast Asia. The UK’s status as a major travel hub further compounds this risk.
Treatment and Management
There is no specific antiviral treatment for measles. Once infected, care is focused on relieving symptoms and preventing complications. This typically involves managing fever with paracetamol, ensuring adequate hydration, and encouraging rest. In some cases, particularly in young children, vitamin A supplements are given to reduce the severity of the disease.
Infections like ear inflammation or pneumonia, which sometimes arise as complications, may require antibiotics. In rare but severe cases, hospitalisation is necessary, especially if breathing difficulties, seizures, or dehydration occur.
But perhaps the most effective treatment is isolation. Infected individuals are advised to stay home for at least four days after the rash appears to avoid spreading the virus to others, particularly those who cannot yet be vaccinated or who are immunocompromised.
How Can It Be Prevented?
The most effective way to prevent measles is through vaccination. The MMR vaccine, introduced in the UK in 1988, provides around 97% protection after two doses. NHS guidelines recommend the first dose at 12 to 13 months and the second at 3 years and 4 months. Catch-up programmes are available for older children and adults who missed out during childhood.
The UK government, in collaboration with the NHS and UKHSA, has intensified public health messaging and catch-up immunisation drives, especially targeting schools, migrant communities, and underserved populations. Text-message reminders, pop-up clinics, and community outreach programmes have been employed to boost uptake.
In 2024, “Get Vaccinated for Summer”, a national campaign launched across the NHS and Transport for London platforms, aimed to raise awareness among holidaymakers and parents ahead of summer travels.
Staying Safe This Summer
At this present time, when the sun shines brightly and plans stretch far and wide, a few practical steps can make the difference. Checking vaccination status, particularly before travel, is a key starting point. Those unsure can consult their GP or check their NHS app. Also, staying hydrated during hot weather, especially when feeling unwell, is essential. And for those recovering from measles, avoiding excessive heat, resting indoors, and monitoring for complications are important parts of care.
Being mindful of symptoms such as sudden high fever, a persistent cough, and eye irritation can help catch the illness early, especially if someone in the household or school has been recently diagnosed.
Measles remains a potent threat in the UK, particularly due to declining vaccination rates and increasing international mobility. While the virus itself does not depend on seasonal temperatures, the social dynamics of summer, that is, crowded events, travel, and heat stress, create an environment conducive to outbreaks.