OPINION: The Magic Number for Reducing Infections and Keeping Businesses Open

Opinion | The Magic Number for Reducing Infections and Keeping Businesses Open Data from early in the pandemic reveals there’s a “sweet spot.” nytimes

NY Times  op-ed   by Yarna Serkez

While many restaurants, bars and gyms shut down during the pandemic, others have continued operating with limited capacity. New research shows this sacrifice could be effective at curbing transmissions — and density caps may offer one way to keep the economy humming along during the worst of the winter wave.

Data from early in the pandemic reveals there’s a “sweet spot” where infections can be reduced while keeping business steady. That magic number: around 20 percent. If indoor capacity in public spaces like restaurants, gyms, hotels and grocery stores was reduced to just 20 percent, we could prevent 87 percent of new infections. Meanwhile, these businesses would lose just 42 percent of their visits, on average, according to research from scientists at Stanford and Northwestern.

The findings bolster capacity limits as an effective coronavirus strategy, keeping businesses alive while limiting infections. Researchers found they are so effective because they reduce the risks during peak hours, encouraging patrons to stay home or visit at less crowded times, according to Serina Chang, a PhD student at Stanford and co-author of the study.

“Capacity caps disproportionately target those risky locations in their busiest hours. This is why we see the promising trade-off curve, where a smaller reduction in visits can result in a large reduction in infections,” she said.

The finding should influence how cities respond to the pandemic now. Rather than citywide shutdowns and stay-at-home orders, stricter density caps paired with other measures could curb the coronavirus while allowing the economy to limp along.

These findings are consistent with earlier study by researchers at the University of Chicago and Northwestern University, which showed that reducing economic activity in hotspot neighborhoods in New York while keeping businesses open in other parts of the city could prevent the coronavirus from spreading with a “lower economic cost than uniform citywide closure policies.”...