One of the most contagious diseases known to humans. Before vaccination, nearly every child contracted measles.
Measles is a highly contagious viral disease caused by the measles virus (a paramyxovirus). It spreads through airborne droplets and can remain infectious in the air for up to 2 hours.
Before the introduction of the measles vaccine in 1963, measles was an almost universal childhood disease. Nearly 100% of children contracted measles by age 15.
Annual reported cases in the U.S. (estimated actual: 4-5 million)
Annual deaths in the U.S. before vaccine introduction
Hospitalizations annually in the U.S. pre-vaccine
The severity of measles was well-documented in medical literature. In the decade before the vaccine, measles was responsible for more deaths than all other vaccine-preventable diseases combined in the United States.
| Dose | Effectiveness |
|---|---|
| 1 dose (at 12-15 months) | 93% |
| 2 doses (school age) | 97% |
| Post-exposure prophylaxis | ~90% if given within 72 hrs |
Due to measles' high transmissibility (R₀ of 12-18), the herd immunity threshold is approximately 95% of the population must be immune to prevent sustained transmission.
After decades of progress, global measles vaccination coverage has plateaued. The WHO reports that measles cases increased 79% globally in 2023-2024 compared to the previous year.
Low Vaccination Coverage
Communities below 95% threshold
International Travel
Unvaccinated travelers import cases
Under-12 Months
Too young for first dose
The measles vaccine is not available as a single-antigen vaccine in most countries. It is administered as combination vaccines:
The most widely used measles-containing vaccine globally. Contains live attenuated viruses.
Schedule: 12-15 months (1st), 4-6 years (2nd)
Contraindications: Severe immunodeficiency, pregnancy, severe allergy
Combination vaccine for measles, mumps, rubella, and varicella (chickenpox).
Schedule: 12-23 months (single dose)
Note: Higher risk of febrile seizures vs. separate vaccines
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