By Jeff Horwitz

Public health officials around the country are facing intimidation both online and off.

Opponents of social-distancing rules are using Facebook Inc. to organize and broadcast protests at the homes of health officials, sometimes using violent rhetoric, in campaigns that health authorities say amount to harassment.

Some of the campaigns against health officials also appear to violate the social-media giant's rules against spreading coronavirus misinformation, by encouraging people to defy public-health directives on mask use that are based on widely accepted scientific thinking on combating the virus.

"Hey public health officers you're in our cross hairs," a group of re-opening advocates calling themselves the Freedom Angels wrote recently. In a live video, one of its leaders, Denise Aguilar, demanded the repeal of mask-wearing mandates and called public health officers "public enemy number one."

Along with other members of the group, she's been livestreaming protests outside of public health officers' homes to their 22,000 followers. The group has said it is committed to keeping its protests peaceful.

Facebook told The Wall Street Journal that live-streaming protests held at health officers' homes violates its privacy rules and removed three such posts from the group. Facebook's rules ban harassment and doxxing, the practice of putting people's personal information on the internet so they can be harassed by others.

The company hasn't taken action on other posts in which the group seeks to recruit protesters for future events or promotes claims that wearing masks can cause oxygen deprivation. In April, as re-open protests began in Michigan, Facebook pledged it would remove posts that encouraged people to attend protests in violation of public health orders or provided false information about coronavirus precautions.

A spokeswoman didn't respond to questions about why Facebook wasn't taking down posts from the Freedom Angels or similar groups that advocated for protesting in ways that violated health orders.

"Certainly saying that social distancing is not effective to help limit the spread of coronavirus, we do classify that as harmful misinformation and we take that down," Facebook founder and Chief Executive Mark Zuckerberg said in an April interview about Covid falsehoods.

Some of the central arguments of mask opponents -- such as claims that masks don't offer significant protection from the virus or lead to potentially fatal oxygen deprivation -- rely on information deemed false by Facebook fact checkers. While that designation slows the spread of the original post on Facebook, it doesn't affect nearly identical claims in reopen protesters' new posts and live videos.

"An increasing number of public health officials, across the country -- myself included -- are threatened with violence on a regular basis," said Barbara Ferrer, director of Los Angeles County's public health department. "In my case, the death threats started last month, during a Covid-19 Facebook Live public briefing when someone very casually suggested that I should be shot."

In the debate about reopening the U.S., masks have emerged as a flashpoint, with some saying mandates either a manifestation of the nanny state or a slippery slope toward increasingly totalitarian conditions.

There is no evidence that the masks are harmful for adults, and scientists have reported such measures are essential for society to reopen without a spike in disease and deaths. The U.S. Centers for Disease Control and Prevention says everyone should wear cloth face coverings in public except children under age 2 and those who have trouble breathing.

In Orange County, Calif., protestors used Facebook to target the county's chief health officer, Dr. Nichole Quick, after her department issued a requirement for residents to wear face coverings outside their homes when social distancing wasn't possible. Dr. Quick resigned this month, and the county backed down, recommending face coverings instead of requiring them.

In that instance, the protesters used Facebook to share pictures of a banner depicting Dr. Quick with a Hitler mustache in front of a swastika and spread allegations that her mother had been photographed outdoors without a mask.

Ohio's top public health official, Dr. Amy Acton, also resigned this month after armed protesters showed up at her house to register their displeasure with her role in the state's efforts to stop the spread of the coronavirus. Facebook groups explicitly devoted to her firing gathered more than 4,000 members.

Dr. Acton and Dr. Quick couldn't be reached for comment.

Kat DeBurgh, head of the California Public Health Officers Association, said social-media fueled harassment of public health officers had contributed to the burnout of public health officers already working long hours during the pandemic.

Seven of California's 61 public health officers have stepped down since the beginning of the crisis, she said, one directly because of protests targeting her personally. Another is now under around-the-clock protection from the county sheriff due to credible threats.

"There's definitely a place for public comment, but this has crossed into intimidation," Ms. DeBurgh said about the protests at her members' family residences.

The outpouring of anger toward public health officers has caught the profession by surprise, said Lori Freeman, chief executive of the National Association of County and City Health Officials.

"This has traditionally been a very trusted community partner role," she said. Public health officers are trying to take criticism of coronavirus restrictions into account, she said, calling protests at their homes inappropriate.

"We've had instances in Colorado where protesters have thrown rocks through the local health department window," she said.

In a Facebook video, one of the Freedom Angels organizers called the tactics directed at Dr. Quick generally appropriate. "For the first time, she was being held accountable to her community," said Tara Thornton, a founding member of the Freedom Angels.

A representative for the Freedom Angels asked for written questions from the Journal, however, the group didn't respond to them when sent.

On June 14, the Freedom Angels held a protest in front of the home of Chris Farnitano, the public health officer for Northern California's Contra Costa County.

Citing concessions won following the protests in Orange County, the group asked viewers on Facebook to sign up as "boots on the ground." They returned to Dr. Farnitano's home two days later.

In a podcast Monday, Dr. Farnitano said the protests were unsettling.

"We've stepped up security around my home," he said, adding that his wife "didn't sign up for public harassment."

Write to Jeff Horwitz at Jeff.Horwitz@wsj.com