The world really has turned upside down. In 2007 San Francisco became the first large city in the country to ban single-use plastic bags. Now, as part of its effort to combat the spread of COVID-19, the city is banning the reusable tote bags it's spent over a decade promoting.

Last week, the San Francisco Department of Health published an update to its guidelines for the city's already strict shelter-in-place order. These new guidelines include social distancing protocols that so-called "essential" businesses must follow when applicable.

Included in the protocol section on preventing unnecessary contact is a directive for businesses to prohibit customers from bringing their own bags, mugs, or other reusable items from home.

As SFGate notes, the updated guidance does not address the status of the city's existing plastic bag ordinance, which bans the distribution of non-compostable single-use plastic bags, and requires stores to charge ten cents for each compostable, paper, or reusable bag a customer uses. That fee is set to increase to 25 cents in July 2020.

Both New York and Maine have suspended the implementation of their state-level plastic bag bans because of the novel coronavirus.

John Tierney argued in CityJournal recently that reusable bags have the potential to become contaminated with bacteria and have been known to transmit viruses. Early studies show that COVID-19 can also survive on plastic surfaces for up to three days.

That suggests reusable bags, which are often made of plastic, might create additional risks for grocery store customers and staff. If a person brings a reusable bag from a home where someone is sick, any clerk who handles that bag could end up getting infected. And if that clerk is already sick, a bag that doesn't immediately get tossed in the trash could end up infecting the next person who comes into contact with it.

However, the CDC had downplayed the risks that people will pick up COVID-19 from surfaces, saying that it is much more likely to get the virus from another person. Two epidemiologists who spoke with Slate about grocery store best practices in the time of coronavirus were also dismissive of the idea that reusable bags created additional risks.

The fact that we're still in the dark about how best to prevent the spread of coronavirus is actually a good reason to not have bag bans of any kind, reusable or single-use.

Stores that are particularly concerned about the risks of a customer bringing in a contaminated reusable bag should be free to opt for allowing (and providing) only single-use bags. Shoppers who like their reusable bags, or who are concerned about bringing home single-use plastic bags that might have been handled by sick staff, should also have the option of patronizing places that still allow their preferred receptacle.

The San Francisco Chronicle reports that some grocery store chains came up with a middle-ground policy of allowing customers to bring their own reusable bags on the condition that they bag items themselves.

It's fashionable to say that there are no libertarians in a pandemic. Yet preserving freedom of choice, even about the small things like which bag to use at the grocery store, allows people and businesses to react more nimbly to uncertain risks.

That San Francisco has had to oscillate between two totally different prohibitions, meanwhile, highlights the problem of always picking the most restrictive top-down solution for any given problem.