7 reasons why measles is more dangerous than you think
From hidden immune damage to delayed brain disease, measles carries risks that extend far beyond a childhood rash.
- 24 February 2026
- 5 min read
- by Linda Geddes
Measles is highly contagious, deadly and yet preventable with a safe, effective vaccine. While millions worldwide deal with the lifelong complications caused the virus, some choose to downplay the threat.
Here are seven reasons why measles is more dangerous than you might think.
1. Measles is one of the most contagious diseases known to man
Measles virus spreads through coughing and sneezing, or by breathing in particles exhaled by an infected person. The virus remains active in air or on infected surfaces for up to two hours, making it extremely infectious.
Until recently, when better vaccination coverage caused cases to decrease, measles was the single leading cause of sight loss among children in low-income countries, causing 60,000 kids to go blind each year.
One person carrying measles virus can infect up to 18 further people in populations where no one has any immunity to the virus.
In reality, most populations have some immunity, but outbreaks can still spread quickly: during a measles epidemic in the Cox’s Bazar refugee camps in Bangladesh in late 2017 – where many Rohingya children had missed out on routine vaccines – each case infected an estimated 1.4–4.3 others before reactive vaccination campaigns slowed transmission.
The virus can also be transmitted by an infected person up to four days before the characteristic rash appears, making it even harder to contain the spread.
2. Severe complications are relatively common
Although most people with measles recover, measles is far from just a rash.
In countries with well-resourced healthcare systems, complications occur in 10–20% of people who catch measles. These can include pneumonia in one to six percent of cases; convulsions in about 1 in 200 cases and encephalitis (brain swelling) in about 1 in 1,000 cases.
In the US, of the 4,056 people who caught measles between 2001 and 2022, 727 (18%) were hospitalised and three died.
One person carrying measles virus can infect up to 18 further people in populations where no one has any immunity to the virus.
Complication rates can be substantially higher in lower-income settings, particularly where malnutrition is common. Vitamin A deficiency, for example, is associated with more severe disease and complications, including blindness.
Until recently, when better vaccination coverage caused cases to decrease, measles was the single leading cause of sight loss among children in low-income countries, causing 60,000 kids to go blind each year.
Certain groups are also at greater risk of complications – including children under five and adults over 30 – while measles infection during pregnancy is linked to a higher risk of severe illness, and increases the risk of miscarriage, stillbirth, premature birth and low birth weight.
3. Hidden complications can emerge months or years later
For some people, the damage caused by measles does not become apparent until long after the initial infection has cleared.
One of the most serious delayed complications is subacute sclerosing panencephalitis (SSPE), a rare but often fatal brain disorder that can develop years after a seemingly routine case of measles, and which gradually destroys memory, movement and awareness.
In the US, of the 4,056 people who caught measles between 2001 and 2022, 727 (18%) were hospitalised and three died.
Even in people who never develop such complications, measles can quietly reshape the immune system by depleting its memory of previous unrelated infections. This so-called “immune amnesia” leaves measles survivors more vulnerable to diseases they had previously learned to fight.
For instance, in a study of 77 unvaccinated children, researchers found that measles infection eliminated between 11% and 73% of the antibody repertoire targeting other pathogens in blood samples taken before and after catching measles.
4. There’s no specific treatment
Once a measles infection has begun, there’s no specific antiviral drug that can cure it or shorten its duration. Instead, treatment is limited to supportive care: managing fever, dehydration and complications such as pneumonia or secondary bacterial infections.
Once a measles infection has begun, there’s no specific antiviral drug that can cure it or shorten its duration.
This is why prevention is so crucial: vaccination doesn’t just lower the risk of infection –it also helps prevent the serious complications measles can cause.
5. Vaccination coverage needs to be unusually high to stop measles spreading
Because measles is so contagious, stopping it requires exceptionally high vaccination coverage compared with most infectious diseases: about 95% of people need to be immunised to prevent sustained transmission.
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If coverage falls even a few percentage points below this threshold, immunity gaps can emerge, allowing the virus to spread rapidly through clusters of unvaccinated people. Even in countries with high national vaccination averages, some regions or communities may have lower levels of immunity, leaving them at greater risk.
6. Some people can’t be immunised or aren’t fully protected by vaccines
Not everyone can be protected by vaccination, which is one reason measles remains dangerous even in highly immunised societies.
Some people cannot receive the vaccine at all, including infants who are too young, people with certain immune disorders and those undergoing treatments such as chemotherapy.
One of the most serious delayed complications is subacute sclerosing panencephalitis (SSPE), a rare but often fatal brain disorder that can develop years after a seemingly routine case of measles, and which gradually destroys memory, movement and awareness.
Others may be vaccinated but still not fully protected, as no vaccine is 100% effective. This means protection against measles depends not only on individual vaccination, but on maintaining high immunity across the wider community so the virus has less opportunity to reach those who remain vulnerable.
7. Measles doesn’t just affect individuals – it disrupts communities
Because the measles virus is airborne and can linger in the air for up to two hours, suspected cases must be isolated immediately.
Healthcare workers exposed to the virus may be required to stay home if their immunity is uncertain, reducing staffing capacity, while clinics and wards may need to temporarily adjust services to enable infection control measures and contact tracing.
Schools can also be affected: during outbreaks, public health authorities may exclude unvaccinated students to limit spread. Parents may deliberately keep their children home as a precaution, disrupting education and forcing parents to miss work.
During a major measles outbreak in Texas in 2025, student absences in a district at the heart of the event climbed 41%, an impact about ten times greater than expected from the number of confirmed infections, reflecting the broader disruptions such outbreaks can cause.
