The current measles outbreak spreading across the United States is both alarming and completely unnecessary. It is particularly disturbing because measles is a disease that can be prevented through vaccination. Yet thousands of Americans are becoming infected, and the numbers continue to grow.

According to the Centers for Disease Control and Prevention (CDC), 5,412 confirmed measles cases were reported in the United States as of November 12. There were 2,289 cases in the full year of 2025. These numbers should concern every American.

What makes measles especially dangerous is how easily it spreads. An infected person can transmit the virus through the air by coughing, sneezing, or even breathing. The virus can remain infectious in the air for up to two hours after an infected person has left a room.

Even more concerning, an infected individual can spread measles approximately four days before the characteristic rash appears. During that time, the person may feel well enough to travel, attend school, go shopping, visit relatives, or participate in public gatherings without realizing that they are contagious. One infected individual can expose numerous susceptible people. Up to 90 percent of susceptible individuals who have close contact with someone infected may contract the disease.

As someone who has spent a lifetime teaching medical microbiology and studying infectious diseases, I find the current situation difficult to understand. Have we forgotten what these diseases can do?

Let's talk about herd immunity.

Herd immunity, also called community immunity, occurs when a sufficiently large percentage of a population is immune to an infectious disease, making it much more difficult for the virus to spread. This indirect protection helps safeguard people who cannot be vaccinated, including certain individuals with medical conditions and infants who are too young to receive certain vaccines.

Measles is particularly contagious. Approximately 95 percent of a community needs to be vaccinated to maintain effective community protection. When vaccination rates fall, the protective barrier weakens. Unvaccinated individuals create opportunities for the virus to spread, sometimes resulting in major outbreaks.

The measles outbreak is a perfect example of what happens when vaccination rates decline. We cannot simply assume that herd immunity will protect us. It depends on the willingness of individuals and families to participate in protecting their communities.

Measles is not necessarily a harmless childhood illness. It can cause pneumonia, brain inflammation, permanent neurological damage and death. Other vaccine-preventable diseases, including polio and influenza, can also cause serious complications, permanent disabilities and fatalities.

We have the scientific knowledge and effective vaccines to prevent much of this suffering. The measles, mumps and rubella (MMR) vaccine is approximately 97 percent effective against measles after two doses.

I have spent years writing about immunization and the consequences of infectious diseases. I will continue to do so because public awareness matters.

To those who question the value of vaccination or choose not to immunize their children, I have a simple message: You are not just making a decision for your own family. You are potentially placing others at risk.

Many recommended immunizations are available at little or no cost through health insurance, public health programs and participating pharmacies. Check your vaccination records and speak with your health care provider about what you and your family need.

No one should have to suffer, become permanently disabled, or die from a disease that can be prevented through immunization.

We have the vaccines. We have the scientific evidence. What we need now is the willingness to use them.

Get immunized. Protect your family. Protect your community.