Dr. Stock joined physicians including Dr. Joseph Mercola and a group that calls itself America’s Frontline Doctors, in generating huge audiences for their bogus claims. The statements by them and others have contributed to vaccine hesitancy and a resistance to masks that have exacerbated the pandemic in the United States, public health officials say.

The doctors often stand in lab coats and use simplified medical jargon, lending an air of authority. They often take advantage of a ready audience online by livestreaming news conferences, and keep interest alive by promising new evidence that will expose corruption and support their arguments…

In January, a San Francisco doctor who had been falsely claiming that 5G technology caused the pandemic volunteered to surrender his license to the California Medical Board.

“Publicly spreading false Covid-19 information may be considered unprofessional conduct and could be grounds for disciplinary action,” Carlos Villatoro, a spokesman for the Medical Board of California, said in a statement.