Measles Outbreak in Mexico: Vaccination Concerns and the BCG Scar

Mexico is currently facing a significant measles outbreak, raising concerns among the public. Amidst this outbreak, a common question arises: what is the significance of the scar often found on the left arm? Many mistakenly believe it’s from the measles vaccine, but it’s actually a mark from a different, crucial immunization – the Bacillus Calmette-Guérin (BCG) vaccine.

What is the BCG Vaccine and Why Does it Leave a Scar?

The BCG vaccine protects against severe forms of tuberculosis (TB), including tuberculous meningitis. It’s administered to newborns in Mexico as part of the national vaccination schedule established by the Ministry of Health. Tuberculosis remains a deadly infectious disease, causing over a million deaths annually worldwide.

The BCG vaccine is given as an intradermal injection – meaning it’s injected into the skin on the upper arm. This creates a small lesion that eventually heals, leaving a permanent scar. This scar indicates that the body developed an immune response to the vaccine.

It’s key to note that the absence of a scar doesn’t always mean a person isn’t protected, but it can be a reason to check vaccination records.

How Do You Know if You’ve Received the Measles Vaccine?

The measles vaccine is typically administered as part of the triple viral vaccine (SRP), which also protects against rubella, and mumps. In Mexico, it’s generally given at one year of age, with a booster dose at six years of age.

If you’re unsure about your vaccination status, you can check your national health card, ask your parents or guardians, or visit a medical center to confirm.

Who Should Gain Vaccinated Against Measles in 2026?

In response to the current outbreak, the Ministry of Health recommends verifying complete vaccination schedules, particularly for:

• Infants 18 months old, for the second dose of SRP
• Children from 6 to 11 months living in areas with active outbreaks
• People under 49 years of age who do not have a complete vaccination schedule or don’t remember being vaccinated

Vaccination modules are available throughout Mexico. You can find the nearest location in Mexico City here.

Current Measles Situation in Mexico

As of February 12, 2026, Mexican health authorities have reported 2,919 confirmed measles cases. This represents approximately 45% of the total confirmed cases reported in all of 2025 (6,432). Since the beginning of 2025 through February 12, 2026, a total of 9,351 confirmed cases, including 28 fatalities, have been reported.

Jalisco state accounts for the majority of cases in 2026, with 1,701 confirmed cases (58% of the national total). Other affected states include Chiapas (296), Mexico City (170), and Sinaloa (150). Two measles deaths have been reported in 2026, one each in Michoacán and Tlaxcala states.

Mexico risks losing its measles-free status, particularly with millions of people expected to arrive for the World Cup.

Measles in the United States (2026)

As of February 12, 2026, 910 confirmed measles cases have been reported in the United States. The majority of these cases (904) are associated with outbreaks in 24 states. Six cases involve international visitors to the United States.