Measles is a highly contagious and serious respiratory infection caused by a virus. Despite the availability of a safe and effective vaccine, measles remains a significant global health concern, leading to severe complications and even death, particularly in young children. Understanding what measles is, how it spreads, its symptoms, and crucially, how to prevent it, is vital for public health and individual well-being.
Measles Overview: A Contagious Viral Disease
Measles, also known as rubeola, is characterized by its extreme contagiousness. The virus spreads through the air when an infected person coughs or sneezes. It’s so contagious that if one person has measles, up to 90% of the people close to that person who are not immune will also become infected. While anyone can get measles, it is most prevalent and often more severe in children.
The measles virus initially infects the respiratory tract, including the nose, throat, and lungs. From there, it disseminates throughout the body, causing a range of symptoms and potential complications. Vaccination is the most effective method to prevent measles infection and its spread.
Prior to the introduction of the measles vaccine in 1963 and its widespread use, measles epidemics were common, occurring roughly every two to three years. These epidemics resulted in an estimated 2.6 million deaths annually. Thanks to global vaccination efforts, significant progress has been made in reducing measles deaths.
However, measles is far from eradicated. In 2023, it’s estimated that there were 107,500 measles deaths globally, predominantly among children under five years old. This stark number underscores the ongoing threat of measles, especially in regions with lower vaccination rates. The Measles & Rubella Partnership, along with organizations like the WHO, have played a crucial role in preventing an estimated 60 million deaths between 2000 and 2023 through accelerated immunization programs. Despite this success, measles remains a persistent challenge, highlighting the need for continued and strengthened global vaccination initiatives.
The Impact of the COVID-19 Pandemic on Measles Control
The COVID-19 pandemic significantly disrupted global health services, including measles surveillance and immunization programs. Lockdowns, healthcare resource diversions, and vaccine hesitancy contributed to a decline in vaccination rates worldwide. This disruption has created a dangerous environment where measles can resurge.
The suspension of routine immunization services and decreased immunization coverage left millions of children vulnerable to measles and other vaccine-preventable diseases. Reduced surveillance also means that outbreaks might go undetected for longer, allowing the virus to spread further within communities.
Measles outbreaks can occur anywhere, and areas with suboptimal immunization coverage become reservoirs for the virus. These areas not only put their own unvaccinated populations at risk but also increase the likelihood of measles spreading to other regions and countries. The pandemic has underscored the interconnectedness of global health and the fragility of progress made in disease elimination.
To regain ground and meet global measles elimination goals, it is imperative to strengthen immunization programs as part of primary healthcare systems. Efforts to reach every child with two doses of the measles vaccine must be accelerated. Furthermore, robust surveillance systems are essential to identify and address immunity gaps, enabling timely responses to prevent and control outbreaks. The lessons learned from the pandemic highlight the need for resilient and adaptable healthcare systems to maintain essential services like immunization, even during global health crises.
Recognizing Measles: Signs and Symptoms
Measles symptoms typically appear 10 to 14 days after exposure to the virus. The most distinctive sign of measles is the characteristic rash.
The initial stage of measles, often lasting 4 to 7 days, is marked by flu-like symptoms:
- Runny nose (coryza): A clear discharge from the nose is common.
- Cough: A persistent dry cough develops.
- Red and watery eyes (conjunctivitis): Eyes become inflamed, red, and sensitive to light.
- Koplik spots: These are small, white spots that appear on the inside of the cheeks. They are a hallmark sign of measles and occur before the rash.
The measles rash typically emerges about 7 to 18 days after exposure. It usually starts on the face and upper neck. Over the following three days, the rash spreads downwards, covering the entire body, including the hands and feet. The rash itself is characterized by flat, red spots that may merge as they spread. It typically lasts for 5 to 6 days before gradually fading.
It’s important to note that most measles-related deaths are not directly from the virus itself, but from complications arising from the infection.
Measles complications can be severe and life-threatening, including:
- Blindness: Measles can lead to vitamin A deficiency and damage the optic nerve, causing blindness.
- Encephalitis: This is a serious complication involving inflammation of the brain, which can lead to brain damage, seizures, and neurological problems.
- Severe diarrhea and dehydration: Measles can cause significant gastrointestinal distress, leading to severe dehydration, particularly in young children.
- Ear infections (otitis media): Bacterial ear infections are a common secondary complication of measles.
- Pneumonia: Measles can cause severe lung infections, including pneumonia, which is a leading cause of measles-related deaths.
If a pregnant woman contracts measles, it poses serious risks to both the mother and the baby. Measles during pregnancy can increase the risk of premature birth and low birth weight in infants.
Complications are more frequent and severe in certain populations, particularly children under 5 years old and adults over 30. Malnourished children, especially those with vitamin A deficiency or compromised immune systems due to conditions like HIV, are also at higher risk of severe complications. Measles itself weakens the immune system, making individuals more susceptible to secondary infections, and can even cause “immune amnesia,” where the body forgets how to fight off previously encountered infections.
Who is Most Vulnerable to Measles?
Anyone who is not immune to measles is susceptible to infection. Non-immune individuals include those who have not been vaccinated and those who were vaccinated but did not develop full immunity (although this is rare with the measles vaccine).
However, certain groups are at significantly higher risk of severe measles and its complications:
- Unvaccinated young children: Infants and young children who have not yet received the measles vaccine are the most vulnerable population.
- Pregnant women: As mentioned earlier, measles infection during pregnancy carries significant risks.
- Immunocompromised individuals: People with weakened immune systems due to HIV, cancer, or certain medications are at increased risk of severe disease.
- Individuals with vitamin A deficiency: Vitamin A plays a crucial role in immune function, and deficiency increases the severity of measles.
Measles remains endemic in many parts of the world, particularly in regions of Africa, the Middle East, and Asia. The overwhelming majority of measles deaths occur in countries with low per capita incomes and weak healthcare infrastructures that struggle to deliver vaccines to all children.
Furthermore, humanitarian crises such as natural disasters and conflicts can exacerbate measles risk. Damage to health infrastructure and disruptions to health services in these situations interrupt routine immunization programs. Overcrowding in refugee and displacement camps also increases the risk of measles transmission. Children suffering from malnutrition or other conditions that weaken their immune systems are at the highest risk of death from measles in these settings.
How Measles Spreads: Transmission and Contagiousness
Measles is renowned as one of the most contagious infectious diseases globally. It spreads through airborne transmission, primarily via:
- Respiratory droplets: When an infected person coughs or sneezes, they release tiny droplets containing the measles virus into the air.
- Airborne transmission: These virus-laden droplets can remain suspended in the air for up to two hours in enclosed spaces. Breathing in air contaminated with the virus is a highly efficient route of transmission.
- Direct contact: Contact with infected nasal or throat secretions can also spread the virus, although airborne transmission is the primary mode.
The measles virus is remarkably stable in the air and on surfaces, remaining active and contagious for up to two hours. This contributes to its exceptional contagiousness. It’s estimated that a single person infected with measles can infect nine out of ten susceptible close contacts (those who are unvaccinated and have not had measles before).
An infected person is contagious for a significant period: from four days before the measles rash appears to four days after the rash erupts. This prolonged period of contagiousness facilitates rapid spread within communities, especially in settings like schools and childcare facilities.
Measles outbreaks can lead to a surge in severe complications and deaths, particularly among young, malnourished children and vulnerable populations. In countries that have achieved or are close to measles elimination, imported cases from other countries remain a significant source of infection, highlighting the global nature of measles control efforts.
Measles Treatment and Management
Currently, there is no specific antiviral treatment to cure measles. Medical care focuses on supportive measures aimed at alleviating symptoms, ensuring patient comfort, and preventing complications.
Key aspects of measles management include:
- Rest and hydration: Adequate rest and drinking plenty of fluids are crucial to support the body’s recovery and prevent dehydration, especially if diarrhea or vomiting occurs. Oral rehydration solutions can be used to replace lost electrolytes.
- Symptom relief: Medications can help manage specific symptoms:
- Fever reducers and pain relievers: Acetaminophen or ibuprofen can help reduce fever and alleviate pain.
- Cough medicine: Cough suppressants may provide some relief from coughing.
- Vitamin A supplementation: The WHO recommends that all children and adults diagnosed with measles receive two doses of vitamin A supplements, administered 24 hours apart. This helps to restore depleted vitamin A levels, even in well-nourished individuals. Vitamin A supplementation has been shown to reduce the risk of eye damage, blindness, and measles-related mortality.
- Antibiotics for secondary infections: Antibiotics are not effective against the measles virus itself, but they may be prescribed to treat bacterial complications such as pneumonia, ear infections, or eye infections that may develop as secondary infections.
It’s crucial to seek medical advice if you or your child develops symptoms of measles. While there is no specific cure, medical professionals can provide guidance on managing symptoms, monitoring for complications, and ensuring appropriate supportive care.
Preventing Measles: The Power of Vaccination
Vaccination is the cornerstone of measles prevention and the most effective strategy to control and eliminate the disease. Measles vaccination is safe, highly effective, and inexpensive.
Key points regarding measles prevention through vaccination:
- Universal childhood vaccination: Global health recommendations emphasize that all children should be vaccinated against measles.
- Two-dose schedule: Two doses of the measles vaccine are necessary to ensure optimal immunity. The first dose is typically given at 9 months of age in areas where measles is common and at 12–15 months in other countries. A second dose is recommended later in childhood, usually between 15–18 months or at 4-6 years of age, depending on the national immunization schedule.
- Vaccine types: The measles vaccine is available as a single-antigen vaccine or more commonly in combination vaccines, such as the MMR vaccine (measles, mumps, rubella) and MMRV vaccine (measles, mumps, rubella, varicella). Combination vaccines simplify administration and provide protection against multiple diseases with a single injection.
- Measles vaccine effectiveness: The measles vaccine is highly effective. One dose provides approximately 93% protection, and two doses increase protection to about 97% against measles.
- Global vaccination efforts: Routine measles vaccination programs, combined with supplementary immunization activities like mass vaccination campaigns in high-risk areas, are crucial for reducing global measles incidence and mortality. The measles vaccine has been in use for approximately 60 years and costs less than US$1 per dose, making it a highly cost-effective public health intervention.
- Emergency vaccination: Measles vaccines are also strategically used in emergency situations, such as outbreaks and humanitarian crises, to prevent further spread of the virus, particularly among vulnerable populations like refugees.
Despite the proven effectiveness of the measles vaccine, significant gaps in vaccination coverage persist globally. In 2023, only 74% of children worldwide received two doses of the measles vaccine, and approximately 83% received at least one dose by their first birthday. Around 22 million infants missed at least one dose of measles vaccine through routine immunization services in 2023, highlighting the ongoing challenge of achieving and maintaining high global measles vaccination coverage.
WHO’s Role in Global Measles Elimination
The World Health Organization (WHO) plays a leading role in global measles control and elimination efforts.
Key WHO initiatives and strategies include:
- Immunization Agenda 2030 (IA2030): Endorsed by WHO and global stakeholders in 2020, IA2030 sets ambitious targets for immunization coverage, including measles, aiming to achieve regional measles elimination goals as a core indicator of health system performance in delivering essential childhood vaccines.
- Measles and Rubella Strategic Framework 2021–2030: Published by WHO in 2020, this framework outlines seven strategic priorities necessary to achieve and sustain regional measles and rubella elimination targets. These priorities encompass strengthening immunization systems, enhancing surveillance, improving case management, and fostering research and innovation.
- Global Measles and Rubella Laboratory Network (GMRLN): WHO continues to strengthen the GMRLN, a network of laboratories worldwide, to ensure timely and accurate diagnosis of measles and track the genetic diversity and spread of measles viruses. This network is crucial for guiding targeted vaccination activities and monitoring progress toward elimination.
- The IA2030 Measles & Rubella Partnership (M&RP): The M&RP, formerly the Measles & Rubella Initiative, is a global partnership led by key organizations including the American Red Cross, United Nations Foundation, CDC, Gavi, UNICEF, and WHO. The Partnership supports countries in planning, funding, and implementing measles and rubella control and elimination programs, with the overarching goal of ensuring no child dies from measles or is born with congenital rubella syndrome.
Despite substantial progress in reducing measles deaths, the WHO emphasizes that measles elimination remains under threat due to persistent gaps in vaccination coverage and recent setbacks caused by the COVID-19 pandemic. Sustained commitment, strengthened immunization systems, and robust surveillance are essential to achieve and maintain measles elimination goals and protect vulnerable populations from this preventable disease.
References
- Minta AA, Ferrari M, Antoni S, et al. Progress Toward Measles Elimination — Worldwide, 2000–2023. MMWR Morb Mortal Wkly Rep 2024;73:1036–1042. DOI: http://dx.doi.org/10.15585/mmwr.mm7345a4
