A Southern California pediatrician was placed on probation this week after penning letters four years ago that exempted a toddler from all childhood vaccinations. But the doctor maintains he did “nothing wrong.”

Dr. Bob Sears, an outspoken critic of mandatory vaccinations, will be under scrutiny for 35 months following the decision by the Medical Board of California.

The Orange County, Calif., pediatrician is accused of failing to obtain a detailed medical history before writing the 2014 letters, which he wrote after the 2-year-old’s mother described the child's adverse reaction to an earlier vaccination, according to officials.

The doctor said it ended up taking more than a year to receive the boy's medical records, which would include the child’s history of immunizations.

Sears said he took the boy’s mother at her word when she said her son lost urinary function and “went limp” in response to previous vaccinations, the Los Angeles Times reported.

"Isn't it my job to listen to my patients and believe what a parent says happened to her baby? Isn't that what ALL doctors do with their patients?” Sears wrote in a Facebook post. “A patient's word is often the only evidence we have — as doctors we must trust our patients, the same way our patients trust us to look out for their best interest.”

He said he agreed to a settlement with the state medical board, which was signed Wednesday, because "it was likely that I'd get probation anyway," and to avoid going to trial, the report said.

“After all, I don’t want a child to receive a medical treatment that could cause more harm. I am going to, first, do no harm, every time,” he added in his post, alluding to a famous medical phrase.

Sears can continue to practice medicine, but will need to take an ethics class and 40 hours of medical education courses a year, the Times reported.

During his probation period, he must also be monitored by another licensed doctor, the Orange County Register reported.

The board also requires Sears to notify all locations where he practices within seven days of the order going into effect July 27, according to the Register.

“It’s not a trivial decision, it’s not a slap on the hand,” Dorit Reiss, a University of California, Hastings law professor, told the Times. “It really is strongly limiting his ability to practice. … He’s a doctor under supervision now.”

Rebecca Estepp, who is part of an advocacy group for alternative vaccine schedules, supports Sears.

“Many parents, myself included, are relieved that Dr. Sears will maintain his practice and continue to serve his patients that rely on him,” Estepp told the Times.

Probation is the most common punishment for doctors in California accused of wrongdoing.

But Sears said that the board had four additional cases pending against him.

“It seems there is an attempt to keep me on probation for the rest of my medical career,” Sears wrote on Facebook.

The state medical board took away 57 licenses, while putting 197 doctors on probation in the last fiscal year, according to the Times.