“Scientific intuition does tell you something,” Dr. Longini said. “It’s just that you can’t quantify it very well.”
Maria Polyakova, an economist at Stanford University, has studied the effects of the pandemic on the U.S. economy. “In general,” she said, “we expect that staying at home mechanically slows the pandemic, as it reduces the number of interactions between people.”
“The trade-off is that the reduction in economic activity especially hurts many workers and their families in the large service sector of the economy,” she added. So is the curfew worth the price?
She is at a loss to understand the logic. “Assuming that nightclubs and such are already closed down anyway, for instance, prohibiting people from going for a walk around the block with their family at night is unlikely to reduce interactions,” Dr. Polyakova said.
Moreover, the virus thrives indoors, and clusters of infection are common in families and in households. So one daunting question is whether forcing people into these settings for longer periods slows transmission — or accelerates it.
“You can think of it like this,” said William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, “what proportion of transmission events happen during the time in question? And how will the curfew stop them?”
One study, published recently in Science, analyzed data from Hunan Province, in China, at the start of the outbreak. Curfews and lockdown measures, the researchers concluded, had a paradoxical effect: These restrictions reduced the spread within the community, but raised the risk of infection within households, reported Kaiyuan Sun, a postdoctoral fellow at the National Institutes of Health, and his colleagues.