Measles Outbreaks: Vaccine, Symptoms & Prevention Tips

Measles outbreaks can cause serious health complications and even death, especially in children under the age of 5. Measles is a highly contagious airborne viral infection that affects only humans and is one of the leading causes of mortality in children under the age of 5 worldwide, says Dr. Cecilia Di Pentima, chief of Pediatric Infectious Diseases, professor in the Department of Pediatrics UMass Chan Medical School-Baystate.

The virus, which can lead to severe complications or even death, has been experiencing a resurgence in many parts of the world in recent years, including the United States. Outbreaks are more likely to occur in communities where groups of people are unvaccinated.

Measles caused approximately 500 deaths per year in the United States prior to the introduction of the live-attenuated vaccine in 1967, Dr. Di Pentima explains, and in 1989, the U.S. Public Health Service recommended a two-dose schedule. After implementation of the new immunization schedule, the number of cases dropped by 99 percent. Today, measles is no longer considered an endemic disease in the U.S.

How Does Measles Spread?

Transmission occurs by contact with a patient who has measles. Infectious respiratory droplets from an infected person can remain suspended in the air for up to two hours. Therefore, face-to-face contact is not needed to become infected.

Public spaces, schools, airplanes, and airports are potential sources of outbreaks from airborne exposure to a single infected person, even if this person has not yet developed symptoms.

“Individuals who have not been vaccinated, did not respond to the vaccine or lose vaccine protection because of a weak immune system (immunocompromised) are at 90 percent risk of becoming infected,” says Dr. Di Pentima.

Is Measles Still a Threat?

The World Health Organization in 2002 declared the elimination of measles on the American continent, but the disease could not be eradicated because of imported cases from other parts of the world.

Since 2008, the number of cases of measles began to increase, with the highest number of cases in the U.S. confirmed in 2019 at 1,282. According to the Morbidity and Mortality Weekly Report (MMWR) 2019, most of the cases occurred in outbreaks of unvaccinated individuals living in under-vaccinated communities. Most cases imported from other countries happened in unvaccinated U.S. residents returning to the States. While the U.S. is considered measles-free, the American continent lost its elimination status after measles became endemic in Venezuela in 2018 and Brazil in 2019, according to the MMWR 2021.

Dr. Di Pentima says published data estimates that the risk of becoming infected if not previously vaccinated or infected with measles is 224 higher than for those who are immunized.

Number of Measles Cases Dropped in 2020

In 2020, the number of cases in the U.S. dropped because of mitigation strategies recommended to prevent COVID-19 infections and decreased surveillance. However, the pandemic also limited access to preventive care and immunizations favoring the spread of preventable diseases, including measles, worldwide.

Symptoms of Measles

The main symptoms of measles include:

• Fever
• Malaise
• Rash
• Cough
• White spots in the mouth
• Stuffy or runny nose
• Pink eyes or conjunctivitis

Symptoms typically begin 7-14 days after infection.

Complications of Measles

Complications are responsible for the high mortality rate seen with this infection in children. Some complications include:

• Pneumonia
• Encephalitis (inflammation of brain tissue)
• Myocarditis (infection of the heart)
• Diarrhea
• Ear infection
• Superimposed bacterial infections
• Subacute sclerosing panencephalitis (also known as Dawson disease, a rare form of progressive brain inflammation) is a fatal complication that can occur 7-10 years after measles infection

Who is Most at Risk?

• Children younger than 5 years of age
• Adults older than 20 years of age
• Pregnant people
• People with weakened immune systems, such as from leukemia or HIV infection

How to Prevent Measles

Measles, mumps, and rubella (MMR) immunization, which has been deemed safe and effective by the CDC and FDA, is the best prevention strategy against measles, says Dr. Di Pentima. A single dose of the measles vaccine provides 95 percent protection against infection, and that increases to 96 percent after the second dose.

The first dose of MMR vaccine should be administered at 12 through 15 months of age, and the second dose is recommended before starting school, she explains. When more than 95 percent of people in a community are vaccinated, most people are protected through community immunity or herd immunity.

In an outbreak, or before international travel, this recommended schedule can be modified to provide protection at a younger age, or to boost protection by reducing the interval between doses. The recommendations must be discussed with a physician. Measles outbreaks can be stopped through early diagnosis and notification of cases, isolation of infectious cases, and identifying contacts.

How is Measles Diagnosed?

Measles should be diagnosed by a doctor or other healthcare professional based on the patient’s symptoms, a physical exam, and medical history. A doctor might order lab tests, including:

• Blood test to check for antibodies
• Throat or nose swab to test for the virus
• Urine sample to check for the virus
• Buccal (mouth) scrapings, which involve gently scraping cells from inside the cheeks

How is Measles Treated?

There is no active antiviral medication against measles, therefore, treatment is aimed at alleviating symptoms and includes:

• Fluids
• Fever-reducing medicine
• Antibiotics in the event of superimposed bacterial infections
• Vitamin A supplements, especially in young children, might be helpful in preventing complications

Dr. Di Pentima says that during an outbreak, early diagnosis and quarantine of infected and at-high-risk exposed individuals are the keys to halting transmission. The second intervention is immunization. Postexposure prophylaxis – getting the vaccine - within 72 hours of exposure could prevent or lessen the clinical course of measles in children and adults exposed to measles.

Immune globulin – a medicine that prevents or reduces the severity of infections - is an alternative for those who cannot receive the vaccine, she explains. Dosing and immunoglobulin recommendations differ based on age of the patient and their history of prior measles immunizations. These recommendations must be discussed with a primary care provider who can determine the best intervention for each person exposed.

Ways to Prevent Measles Outbreaks

• Immunization is the best way to prevent measles. The CDC recommends that children get their first dose of the MMR vaccine between 12 and 15 months of age, and their second dose between 4 and 6 years of age. Adults should also get two doses.
• Post-exposure prophylaxis, which can include the administration of a vaccine or immunoglobulin
• Social distancing can include isolation, quarantine, and exclusion
• Hygiene is very important.
• Wash toys and other items with strong detergent
• Wipe down non-washable items with alcohol swabs
• Washing hands and covering your mouth when you cough or sneeze can help prevent the spread of measles

Measles Outbreaks in the U.S.

The CDC shares up-to-date information on measles outbreaks in the U.S., including number and location of cases, age distribution, and vaccination status. For the latest information on measles outbreaks near you, or in places where you plan to travel, reference the CDC’s Measles Cases and Outbreaks reporting.