SEATTLE (AP) — Washington Attorney General Bob Ferguson has sent a letter warning a Seattle-based business to halt selling a so-called COVID-19 “vaccine.”

Ferguson said in a news release Tuesday that if the company, North Coast Biologics, or its owner, Johnny T. Stine, don’t stop making false or unsupported claims about the product, they could be sued under the state Consumer Protection Act.

In a post on Facebook, Stine claims to have developed a “vaccine” that has made him immune to COVID-19, and offers it for $400.

Ferguson notes that no effective treatment or vaccine for COVID-19 has been identified.

In a post on the company's Facebook page, it says the vaccine is no longer available due to a “cease and desist” letter from the AG.

The Associated Press has emailed Stine seeking comment.

“Remember: If something seems too good to be true, it probably is,” Ferguson said. “Scammers take advantage of fear and uncertainty to make you go against your better judgment."