Campbell's cousin, Sarah Wessling, told TMZ that she passed away on December 29.
Her cousin Sarah Wessling said Jessica had worked a normal day seeing patients at her practice before her tragic death. She apparently went to the bathroom and never came out.
Campbell is also survived by husband Daniel, her mother and an aunt, among other extended family members. They said Campbell had congestion, thinking she was coming down with a cold, but the family didn't suspect COVID.
A GoFundMe has been set up in Campbell's honor in order to help her family with funeral expenses, as well as to provide financial aid for her 10-year-old son Oliver. Traveling the world, acting, becoming a doctor, being mom to the coolest kid ever; these bucket list items wove the quotidian fabric of her reality. The results of an autopsy by the Multnomah County Medical Examiner have not yet been shared by her family. She was unable to be revived and her cause of death is to be determined.
And another fan called her "phenomenal" in the role of Tammy Metzler.
Her performance saw her nominated for Best Debut Performance at the Independent Spirit Awards.
Witherspoon also expressed her condolences in a tweet: "So heart broken to hear this".
Jessica leaves behind her 10-year-old son Oliver. Working with Jessica on Election was such a pleasure.
Jessica then became a guest star on hit TV series Freaks and Geeks. Our hearts go out to Jessica's loved ones during this hard time.
"A true adventurer in every sense of the word, Jessica packed a staggering amount of experiences into her tragically short lifetime", the GoFundMe page says.
More than $22,000 has been donated so far, including a $5,000 donation by Freaks and Geeks' executive producer, Judd Apatow.