Some parents say they're concerned not enough children are getting vaccinated, and that is putting infants and other children at risk.
Three-year-old Tyler Grimm of Waverly laughs now, but recently he came down with the chicken pox.
"I had to keep him home from day care, his mother Lilah said.
Chicken pox was an inconvenience but more so a surprise to mother Lilah, because Tyler had been vaccinated against chicken pox, which made her concerned that not enough parents are immunizing their children.
"Because he was vaccinated, his case was very mild."
Dr. Brian Sims said, "When we start having a large number of children not being vaccinated, you're going to see a resurgence in diseases we're trying to prevent."
Sims at Covenant Medical Center in Waterloo says unfounded fears of a link between vaccines and autism have led fewer parents to immunize their children from deadly diseases.
"In Japan we have one in four children not getting vaccinated for anything. Specifically the measles, and so I'm aware the measles rates in japan are skyrocketing. Even deaths."
Sims says cases of measles have emerged in recent years in Iowa, and the rate of whooping cough increased 66 percent last year.
But co-founder of the National Vaccine Information Center Barbara Loe-Fisher said parents still have the right to decide whether to vaccinate or not.
"We feel it's very important for parents to get all the information they can about the risks and complications of infectious diseases, the risks and complications of vaccines. And then sit down with their doctor, ask questions," she said.
Grimm says she does respect parents' rights, but she also wants to make them aware their child could transmit a dangerous disease.
"For a long time all these children's diseases were eradicated: mumps, measles, whooping cough, we all got our shots," she said. "It's just important to get your kids vaccinated."
Even though chicken pox is generally considered mild compared to other diseases, Dr. Sims said before the vaccine, 200 children would die each year in the U.S. from chicken pox-related infections.
Now after the vaccine, that number has gone down to 20 deaths. Doctors say vaccination risks are increasingly small. Possible reactions include a fever or swelling near the vaccination site.