SAN FRANCISCO  — A naturopathic doctor who sold fake COVID-19 immunization treatments and fraudulent vaccination cards during the height of the coronavirus pandemic was sentenced in California on Tuesday to nearly three years in prison, federal prosecutors said.

Juli A. Mazi pleaded guilty last April in federal court in San Francisco to one count of wire fraud and one count of false statements related to health care matters.

During Tuesday’s hearing, U.S. District Judge Charles R. Breyer handed down a sentence of 33 months, according to Joshua Stueve, a spokesperson for the U.S. Department of Justice.

Mazi, of Napa, did not immediately respond to phone calls and an email seeking comment. She was ordered to surrender to the Bureau of Prisons on or before January 6, 2023.

The case is the first federal criminal fraud prosecution related to fraudulent Centers for Disease Control and Prevention vaccination cards for COVID-19, according to the U.S. Department of Justice.

In August, Breyer denied Mazi’s motion to withdraw her plea agreement after she challenged the very laws that led to her prosecution.

Mazi, who fired her attorneys and ended up representing herself, last week filed a letter with the court claiming sovereign immunity. Mazi said that as a Native American she is “immune to legal action.”

She provided fake CDC vaccination cards for COVID-19 to at least 200 people with instructions on how to complete the cards to make them look like they had received a Moderna vaccine, federal prosecutors said.

She also sold homeopathic pellets she fraudulently claimed would provide “lifelong immunity to COVID-19.” She told customers that the pellets contained small amounts of the virus and would create an antibody response, they said.

Mazi also offered the pellets in place of childhood vaccinations required for attendance at school and sold at least 100 fake immunization cards that said the children had been vaccinated, knowing the documents would be submitted to schools, officials said.

Federal officials opened an investigation against Mazi after receiving a complaint in April 2021 to the Department of Health and Human Services Office of Inspector General hotline.

Last year the owner of a Northern California bar was arrested after authorities said made-to-order fake COVID-19 vaccination cards were sold at the establishment to undercover state agents for $20 each.