We’re in the middle of the worst public health crisis in a century, one in which adherence to public health guidelines makes all the difference between an out-of-control pestilence and a serious but containable emergency.

California, at the beginning of the coronavirus pandemic, slowed what looked to be its inexorable spread with an extraordinary yet simple solution:

Shut it all down. Everything.

But aside from the economic consequences of sheltering an entire state in place, public health officials were aware of another reason that asking people to remain totally insulated from the dangers of the coronavirus would have diminishing returns:

From a public health perspective, pasting a proverbial big X over something is frequently a losing bet.

“To get people to change their behavior, to forbid them to do something is not usually successful,” said Dr. John Swartzberg, clinical professor emeritus at the UC Berkeley School of Public Health.

Swartzberg points to the U.S. ban on alcohol, in effect from 1920 to 1933, as a historical example.

<figure id="attachment_1970293" class="wp-caption alignright" style="max-width: 600px"><figcaption class="wp-caption-text">A streetcar conductor in Seattle won’t allow a passenger aboard without a mask in 1918. (U.S. National Archives)</figcaption></figure>

Prohibition, Swartzberg says, was a “puritanical” approach to eradicating real societal ills associated with drinking. But it was ultimately repealed, and it’s widely viewed as a failure due to unintended consequences that included the rise of organized crime through bootlegging and the deaths of people who consumed toxic illegal alcohol.

Today, governments use a well-established strategy called harm reduction to help mitigate the negative effects of not only alcohol but a host of other public health risks, including the spread of COVID-19.

The basic principle behind harm reduction: Don’t tell people they absolutely can’t do something, because it won’t work as well as allowing the behavior, but with added rules to reduce risk.

If Prohibition is a cautionary tale of what happens when harm reduction is left out of the equation, the concept of safer sex is a textbook example of how it can work.

In the earliest days of the HIV crisis, Swartzberg says, health officials promoted an abstinence-only message.

“That clearly didn’t work,” he said, so it was dropped in favor of encouraging people to engage in practices like using condoms and getting tested for the virus.

“We know you’re going to go have sex. But if you’re having sex, here’s what you can do to reduce your risk and your partner’s risk. That was a much more  successful policy. It’s the same thing with what we’re talking about with COVID.”

As scientists continue to work on therapies to address the disease, Bay Area health officials have made one thing clear: Social distancing and masking, ways of reducing risk from the coronavirus, are here to stay for a good while longer. A safe and effective vaccine may be at least several months away; meanwhile all the data has shown that wearing masks and avoiding indoor gatherings are keys to slowing the spread of the disease.

While many months into the crisis people may be suffering mask-wearing and social distancing fatigue, public health experts say the rules are designed to actually allow people more freedom, not less, compared to the constraints of a strict lockdown.

The incremental reopening of different parts of the economy as California counties move through the state’s risk assessment levels is a case in point for how a society can modulate harm reduction in response to changing circumstances. At the highest risk level, the state allows shopping malls to open at 25% capacity; at the next highest, it’s 50%; and at the next, 100%, but with closed common areas and reduced-capacity food courts. In other words, the harm reduction measures ratchet down as the risk subsides.

Buckling Up

Passing safety laws and getting people to embrace them can take years or even decades. While it’s standard practice now for us to buckle up before pulling out of the driveway, modern automobile seat belts weren’t invented until the 1950s, a half-century after Ford brought motorcars to the masses with the Model T. The idea for retractable belts in passenger cars is credited to a neurologist in Pasadena, who’d been treating a large number of patients suffering from head traumas sustained in car crashes.

But the U.S. didn’t require car manufacturers to equip vehicles with seat belts until1968. Even then, no law required passengers to wear them. That occurred in the 1980s, when states began mandating people to buckle up or risk a fine.

With COVID-19, Swartzberg says, we can’t afford that long of an adjustment period; people have to embrace harm reduction now to keep the virus from spreading. Most public health officials agree that the lack of consistent messaging from federal leadership about the efficacy of these practices has been a major barrier to fighting the pandemic in the U.S. For example, a recently released study by Cornell University researchers found that President Trump is “likely the largest driver” of COVID-19 misinformation.

Secondhand Smoke

Some health experts say the lessons learned from anti-tobacco campaigns show that certain strategies may be more effective than others at changing people’s behavior.

Dr. Richard Jackson, professor emeritus at the UCLA Fielding School of Public Health and a former state of California public health officer, says getting to the point where bans were enacted on smoking in public spaces like restaurants, planes and parks took years. What eventually tipped the scales for lawmakers and the American public, Jackson says, was not the message that smoking is bad for you, but rather that lighting up can harm other people.

“It was when we showed that flight attendants were actually getting sick from being in a confined space with a lot of smokers, that was the beginning,” Jackson said. “But eventually, over time, it led to the ban of indoor smoking.”

It wasn’t until 1995 that California paved the way for smoking bans when it became the first state to outlaw smoking in indoor workplaces.

Behavioral economists have a name for actions that affect not ourselves but other people or the whole of society: externalities.

Mask wearing can reduce the externalities of leaving your house during the COVID-19 pandemic because studies show that it helps prevent virus transmission to other people, who may not even know they’re contagious.

When it comes to choosing not to wear a mask, Jackson says, a person might argue: “It’s my life, I can take that risk.” But helping them understand that flaunting this precaution can endanger a child, a loved one, an innocent bystander — what Jackson calls “sympathetic victims” — may encourage holdouts to think twice about ignoring public health orders.

Cultural Differences

The coronavirus pandemic isn’t the first time Americans have been asked to pull masks over their faces, avoid crowds, and subject themselves to a shutdown of parts of the economy to fight a deadly virus.

Doctors prescribed a strikingly similar regimen to fight the 1918 Spanish influenza pandemic, says Dr. Lee Riley, head of the infectious disease and vaccinology division at the UC Berkeley School of Public Health. An estimated 50 million people worldwide and 675,000 in the U.S. died from complications caused by the virus, according to the U.S. Centers for Disease Control and Prevention.

“If you look at some pictures from that period, a lot of people were wearing masks,” Riley said. “They washed their hands, kept social distance, and local governments tried to make sure that people didn’t congregate in large numbers, everything that they’re saying right now.”

Studies suggest public health measures reduced the 1918 flu pandemic <span