Measles: how does it spread and how can I protect my child? | Infectious diseases
A measles outbreak in London is affecting unvaccinated children under 10 and comes amid a global rise in infections.
The UK is one of six countries to lose measles-free status from the World Health Organization (WHO) last month. Experts are calling on governments to urgently increase vaccination rates to prevent measles from infecting more children.
What is measles?
Measles is a highly contagious viral disease that can spread very easily among people who are not fully vaccinated.
It usually starts with cold-like symptoms, followed by a rash a few days later. The rash starts on the face and behind the ears before spreading to the rest of the body.
The spots of the measles rash, which are usually not itchy, are sometimes raised and come together to form blotchy patches. Some people may also have small spots in their mouth.
How is measles spread?
Measles is spread when an infected person breathes, coughs or sneezes. One case can generate 18 secondary infections. Nine out of ten unvaccinated people will get it if they are exposed to it.
A person is contagious from the time they first show symptoms (about four days before the rash appears) until four days after the rash appears.
Health experts recommend opening windows and doors to reduce the risk of spreading measles, washing your hands frequently with soap and warm water, using tissues when you cough or sneeze, and throwing them in the trash immediately afterward.
Sharing cutlery, cups, napkins, clothing or bedding should be avoided.
What are the risks posed by measles?
Although many people recover, the illness can cause serious complications such as pneumonia or inflammation of the brain. In rare cases, measles can cause long-term disability or even death.
Babies and people with weakened immune systems are at greater risk. Measles can also cause miscarriage or stillbirth, premature birth (before the 37th week of pregnancy), and a low birth weight baby.
Despite the availability of a safe and cost-effective vaccine, measles caused 95,000 deaths worldwide in 2024, according to the WHO. Most were unvaccinated children under five.
Why are measles cases increasing?
Measles is entirely vaccine-preventable, but it is highly contagious, so it is among the first diseases to rebound when vaccination rates decline.
Health experts say the growing number of measles outbreaks around the world are occurring as people become wary or skeptical of vaccines following the Covid-19 pandemic.
In January, the UK lost its measles-free status, granted by the WHO if there has been an absence of endemic cases in a country for at least 12 months. Spain, Austria, Armenia, Azerbaijan and Uzbekistan also lost their status.
Experts believe this is a global challenge. Several other European countries already experience regular transmission of measles, notably France and Romania. Canada lost its elimination status in 2025, and the United States is trying to maintain its status as it too grapples with rising infections.
How can the world fight measles?
Herd immunity, fueled by community-wide vaccination, is the only way to prevent measles, with 95% coverage as the threshold, according to the WHO. This figure is high because measles is one of the most infectious diseases in the world, remaining contagious in the air or on surfaces for up to two hours.
In the UK, only 84% of children have received the two doses needed for full protection in 2024. There were 2,911 confirmed cases in England that year, the highest number since 2012.
Globally, the proportion of children receiving a first dose of measles vaccine was also 84% in 2024, below the 2019 level of 86%.
How can I protect my child?
There is no treatment for measles, but two doses of a measles vaccine provide high levels of protection and help prevent further outbreaks.
The MMR and MMR vaccines provide protection against measles, mumps, and rubella, and the MMR vaccine also provides protection against chickenpox. The MMRV vaccine is usually offered to children aged 12 months and 18 months.
What are the signs and symptoms to look out for?
Measles symptoms usually appear 10 to 14 days after exposure to the virus. A large rash is most visible.
The first symptoms usually last between four and seven days. They include runny nose, cough, red, watery eyes, and small white spots on the inside of the cheeks.
The rash appears about seven to 18 days after exposure, usually on the face and upper neck. It lasts three days, finally reaching the hands and feet. It can last up to a week before disappearing.
