A California health official got so many threats after she ordered residents to wear masks that she resigned. Research shows she was right.

• Orange County's former chief health officer resigned after she received threats for issuing a requirement that residents wear face masks in public.
• A few days later, Orange County's district supervisor said masks would be "strongly recommended" instead of required.
• But evidence suggests that mask wearing helps lower coronavirus transmission and prevent deaths.

One of California's wealthiest counties has become a microcosm of the nation's divided response to the coronavirus.

On Monday, the former chief health officer for Orange County, Dr. Nichole Quick, resigned after she received threats for issuing a requirement that residents wear face masks within 6 feet of others in public. Quick is the seventh senior health official in California to resign during the pandemic.

In the days leading up to her resignation, she was the target of mounting public backlash.

Kat DeBurgh, executive director of the Health Officers Association of California, told Business Insider that a group of protesters recently brought a banner depicting Quick as a Nazi to a public Board of Supervisors meeting. Residents also read Quick's home address aloud during a meeting, DeBurgh said, and threatened to protest outside her house.

In response, the Orange County Sheriff's Department provided Quick with a security detail. Quick did not respond to a request for comment.

"I have worked with Dr. Quick for many years and cannot say enough good things about her as a person and a professional," DeBurgh said. "She is optimistic, intelligent, hard-working, and compassionate. These sorts of attacks are heartbreaking and counter-productive when it comes to fighting our common enemy, COVID-19."

Quick issued the mask requirement on May 23, as hospitalization numbers trended upward in Orange County. That same day, the county began to loosen stay-home restrictions, allowing sit-down service at restaurants and reopening some indoor retailers. Daily coronavirus cases in Orange County have been fluctuating, but the county saw its highest number of single-day cases — more than 290 — on June 5. It has reported around 7,700 cases and nearly 150 deaths so far.

A nationwide backlash against mask requirements

In April, hundreds of people gathered in Orange County for demonstrations demanding an end to California's stay-at-home order. Many waved American flags and held signs that called for freedom.

Other protesters across the country have also rallied against requirements to wear masks in public.

On May 1, the day that San Diego instituted its mask requirement, hundreds of protesters gathered outside a local courthouse without any face coverings. The same day, a security guard in Flint, Michigan, was shot and killed after asking a dollar store customer to wear a face mask. Later in the month, a man in Portland, Oregon, was filmed yelling at a grocery-store employee who had asked him to wear a mask inside.

DeBurgh said Orange County public-health officers have been "working tirelessly" to protect their communities from COVID-19. Their weeks are often 80 hours long, she said, and many have not had a day off since February. At the same time, she added, officers like Quick have had to contend with a "mob mentality" that devolves into personal attacks.

"Public comment is an important part of policy-making, but personal attacks benefit no one and will not lead to the best policy decisions," DeBurgh said.

Three days after Quick's resignation, district supervisor Lisa Bartlett announced that a new order was expected to ease the mask requirements. Masks will now just be "strongly recommended" in Orange County — though they will likely still be mandatory in grocery stores and other retail businesses.

Still, evidence suggests that requiring masks is an effective way to protect public health.

Face masks prevent transmission

Quick's mask requirement aligned with recommendations from the Centers for Disease Control, which suggests that people older than 2 years old wear face coverings in settings where it's difficult to maintain social distance. Other California counties, including San Francisco and Los Angeles, have imposed a similar mandate.

A new study from UK researchers found that requiring individuals to wear face masks all the time could be enough to contain an outbreak on its own with no lockdown — even if the masks were only 50% effective at trapping infectious particles when a person exhales.

"These results are striking in that the benefits accrue to the face mask wearer as well as to the population as a whole," the researchers wrote. "There is, therefore, a clear incentive for people to adopt face mask wearing."

The researchers found that face masks can decrease transmission even if just 25% of the population wears them, though not by much. If half of the population wore them, however, that might slow an outbreak (but not prevent it), according to the study. The more people wore face masks, the researchers determined, the closer a community could get to containing its outbreak.

This aligns with research from Arizona State University, which found that "broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19."

The university's models determined that near-universal adoption of face masks in New York state could prevent up to 45% of projected deaths over two months — even if face masks were only 50% effective. In Washington state, face masks that were only 20% effective but worn by most of the population could still reduce mortality by up to 65%, the researchers found.

Still, there is some dissent among public-health experts about whether masks should be a requirement for the general public. When Business Insider recently put the question to 15 leading public-health experts, 11 said masks should be worn, three were uncertain, and one said no. Robert Beardall, who cast the lone dissenting vote, said his answer stemmed from worries that homemade masks would provide a false sense of protection and lead people to get too close to one another.

When Dr. Quick issued Orange County's mask requirement, she cited evidence showing face coverings "can help prevent the transmission of COVID- 19."

"I feel strongly we need a face-covering order in place as we continue to send people out into more social interactions," Quick said.