An Orange County pediatrician and outspoken critic of mandatory vaccinations faces possible discipline by California's medical board.

The Orange County Register reports Friday that Dr. Bob Sears is accused of failing to obtain a detailed medical history before writing a 2014 letter excusing a toddler from immunizations.

The board says Sears wrote the letter after the 2-year-old's mother described an adverse reaction to an earlier vaccination.

If Sears is found negligent, he could face a public reprimand or lose his medical license.

Sears declined comment to the newspaper. The Associated Press also sent an email seeking comment Friday.

Sears has authored a popular book on vaccines and advocates a staggered, alternative vaccination schedule that contrasts with recommendations by the Centers for Disease Control and Prevention.