About two months after my first child was born, there was an outbreak of measles in St. Louis. My daughter was too young to be vaccinated, so she was at risk for becoming infected. Our pediatrician advised us to avoid public places as much as possible.

My daughter was put at risk because some people refused to get their children vaccinated.

People refuse to vaccinate their children for at least two reasons. First, people have forgotten how deadly measles and other contagious diseases can be. Vaccines have been too successful. Before the measles vaccine was introduced in 1963, there were hundreds-of-thousands cases per year and hundreds of people died as a result. Since 2010, we have had at most a few hundred cases per year with almost no deaths. One death occurred in 2015. Cases in this country are often caused by unvaccinated people who travel to other countries and bring the disease back here infecting themselves and others.

These people could use a lesson from my wife. Her father, Max, emigrated to the U.S. with his family when he was 16. They settled in St. Louis in 1904. Max did not speak a word of English. Within 10 years, in 1913, not only did Max speak flawless English, he had his medical degree and became a doctor. Max’s first wife died, and he remarried. My wife was born when her father was nearly seventy.

From the time she was pre-schooler, Carol’s father told her stories about how people suffered and died from contagious diseases. When Carol went to her pediatrician, she was begging the doctor to give her the shots.

The second manifestation is that people do not understand science enough to clearly evaluate the risk from disease and vaccines. Any risk is too much for their children, so they do not vaccinate their kids, and allow other people to take the virtually non-existent risk from vaccines assuming that the other kids protection will prevent their child from getting the disease.

Included in the second manifestation. People who do not use modern medicine because of their religious beliefs. The measles epidemic in 1994 started in such a population.

There are a few problems with these attitudes.

One, it puts their children at higher risk from problems or even death from diseases. Two, it puts other children and adults at risk. The risk group includes children who are too young to get vaccinated and people who cannot get the vaccine for medical reasons, such as weakened immune systems.

Medical experts state that at least 95 percent of the population needs to be vaccinated to protect the at-risk population. In some areas we are at or below that critical threshold.

I do not mind if adults want to put themselves at risk. That is there choice. However, these adults should not be allowed to put other children or other adults at risk. Public safety must always prevail. That is why we must make vaccines mandatory.