The deadliest outbreak of H7N9 bird flu since its discovery in 2013 is sweeping across China. It's caused at least 100 deaths and has been detected in half the country's provinces. So far, the virus seems to be spreading only between birds and the humans who slaughter them for food. But the potential for human-to-human transmission — the trigger for a full-blown pandemic — can't be ruled out. In response, Chinese authorities have temporarily shut down live poultry markets in some of the country's biggest cities.

The strategy has been proven to work, and authorities in China and Hong Kong have deployed it for decades. But every year, so-called wet markets reopen and both new and known viruses reemerge. If authorities won't close such markets permanently — and realistically, they can't, given how large a role the markets continue to play in China's food chain — they need to do far more to fix what's wrong with them. The good news is, that should be relatively cheap and easy to do.

Over the last four decades, the retail experience in China has changed dramatically. Once relegated to state-owned outlets selling drab and shoddily made products, shoppers now flock to malls glitzier and tackier than anything in the West. The wet market — typically a crowded, open-air emporium where individual vendors sell food sourced from local farms and distributors — has stubbornly resisted change. Yet as recently as 2013, some 80 percent of Chinese still chose to buy their fresh vegetables at such places, despite government efforts to promote modern supermarkets.