The UK Health Security Agency (UKHSA) has recently reported an outbreak of measles among unvaccinated children in the north-east of London. Between 1 January and 9 February 2026, 34 laboratory-confirmed cases were reported from a measles ‘hotspot’ in the London Borough of Enfield, where the outbreak affected seven schools and a nursery. These cases accounted for a third (35%) of all confirmed cases in England-a total of 96 over the same period. This spike in measles cases is entirely predictable. According to UKHSA figures published in August 2025, only 64.3% of five-year-olds in Enfield received both doses of the MMR vaccine in 2024/2025. Looking at the bigger picture, 2,911 laboratory-confirmed cases of measles were reported in England in 2024, followed by 959 in 2025. In the light of these figures, the World Health Organisation (WHO) announced, on 26 January 2026, that the UK had lost its measles elimination status.
Across the Atlantic, the situation is even more concerning. According to the Centers for Disease Control and Prevention (CDC), there were 2, 280 confirmed cases of measles in the US in 2025, all of which were urgently notified to the CDC. As of February 12, 2026, 910 cases of measles had already been confirmed for the year, including 904 cases in 23 states and New York City. As many as 962 cases have been notified as of 17 February by the state of South Carolina-an epicentre of the measles outbreak since October 2025. The US had achieved ‘measles elimination status’ in 2000, which was extended to the entire Region of Americas by 2016, making it the first WHO region to achieve this distinction. But in November 2025, the WHO Regional Office for the Americas- the Pan American Health Organisation (PAHO)-declared that the Region of the Americas including the US and Canada, had lost their measles elimination status. This status is unlikely to be regained by the US for many years to come, as non-medical exemptions for mandatory vaccines are accepted by most states. Twenty-nine states and Washington DC allow parents with religious objections to opt-out of school immunisation programmes, while another sixteen states accommodate both personal and religious objections to vaccination.
Measles is caused by the morbillivirus, an RNA virus. It is highly contagious, with a basic reproduction number, or R0, that is often cited as being between 12 and 18. This means that each person with measles could potentially infect, on average, a similar number of susceptible individuals. The R0 may, however, be influenced by demographic, socioeconomic, and environmental factors. The virus is spread primarily by airborne respiratory droplets.
Symptoms of measles usually develop 10 to 14 days after exposure to an infected person. A prodromal illness, characterised by fever and the ‘three C’s’ of cough, coryza (runny nose), and conjunctivitis (red, watery eyes), is followed by a characteristic skin rash or exanthem, which spreads to cover the whole body and is sometimes accompanied by an enanthem which affects the lining of the mouth. The complications of measles can be caused by the virus itself or, more commonly, by secondary bacterial infection. These complications can affect the ears, lungs, bowel, heart, brain, spinal cord, or eyes. Permanent disability can result from blindness, hearing loss, or brain involvement. Children who are either malnourished or immunosuppressed, or both, can be killed by the complications of measles, while pregnant women may suffer miscarriages, premature birth, or stillbirth. The complication rate is stated to be around 10-20% in the developed world, but much higher in poorer countries of the developing world. Adults are more likely to suffer from severe illness and to develop serious complications.
The measles virus was first successfully grown in culture by Thomas Peebles and John Franklin Enders at the Boston Children’s Hospital in 1954. This cultivated strain of virus was isolated from throat swabs and blood samples provided by 11-year-old David Edmonston. The first live attenuated measles vaccine was developed by Enders from the Edmonston-B strain and licensed for public use in 1963 after extensive trials in New York City and Nigeria. A weaker form of the viral strain was used to induce a protective antibody response in recipients. An even weaker version, with less severe side effects, was introduced by Maurice Hilleman in 1968. Hilleman went on to combine the measles vaccine with recently developed vaccines against mumps and rubella in 1971 in the MMR vaccine. The varicella (chickenpox) vaccine was added in 2005 to create the MMRV vaccine. The MMR vaccine was introduced in the UK in 1988, followed by the MMRV vaccine from January 2026. A two-dose regime, consisting of an initial dose, followed by a booster injection, is routine practice.
The falling uptake of MMR vaccination is part of a global phenomenon, variously described as vaccine hesitancy, vaccine scepticism, or vaccine suspicion, which affects people from a wide range of educational, ethnic, cultural, and religious backgrounds. The anti-vaxx movement was energised by the publication of a subsequently retracted paper in a prestigious medical journal, The Lancet, in 1998. Following the paper by Andrew Wakefield and 12 of his colleagues, titled ‘Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children,’ the MMR vaccine was wrongly linked with autism. The case against the vaccine was soon taken on by several celebrities, healthcare professionals operating from the fringes, and alternative healthcare providers. Wakefield’s small case series was subsequently shown to be selective, unrepresentative, and conducted without informed consent. Sadly, despite its suspect methodology, manipulated data, the failure to disclose financial conflicts of interest, and flawed conclusions, the fraudulent paper survived the ‘scrutiny’ of The Lancet’s peer reviewers and editorial board, only to be exposed by the tenacity of a lay person, the investigative journalist Brian Deer, who contributed several articles on the matter to the Sunday Times between 2004 and 2010 and ultimately published a book, The Doctor Who Fooled the World, in 2020. Meanwhile, Wakefield moved to the US, where he found a receptive audience and achieved celebrity status as anti-medical-establishment figure, even as the UK’s General Medical Council struck him off the medical register in May 2010.
Although not responsible for autism, the MMR vaccine can lead to temporary and mild side-effects, such as fever, malaise, local soreness, a skin rash, and swollen lymph glands in the neck. Being a live virus, it must not be offered to pregnant women, people with a weakened immune system, or those who have had a previous serious allergic reaction (anaphylaxis) to any of the ingredients of the vaccine. Serious side-effects, such as purpura (due to depletion of platelets) and encephalitis (inflammation of the brain) are exceedingly rare.
Today’s measles outbreaks are the result of a growing breakdown of trust between healthcare professionals and some sections of the public. It is most important that this trust is regained as soon as possible in the best interests of the wider public, particularly since the MMR vaccine has been shown to be safe and effective. While we should adhere to the well-meaning advice of our public health authorities, we expect them to amplify the benefits of vaccines and to assuage the concerns of the undecided, which may have some justification.
Deaths from the complications of measles, an eminently preventable disease, are a backward step in the progress of humanity. Sadly, according to the WHO an estimated 95,000 people died from measles around the world in 2024, mostly unvaccinated and under-vaccinated children under the age of five years. It is heartening to note, however, that hardly any country in the world, nor any major religion, is opposed to MMR vaccination or its successor, the MMRV vaccine. Japan is a notable exception, having opted for an MR (measles-rubella) vaccine, with mumps vaccine an optional extra. Ultimately, it is to be hoped that good science will prevail and the uptake of MMRV vaccination will increase to a suitable level to allow measles to be eliminated once again.
Ashis Banerjee