
This suggests that travel restrictions weren’t justified later in the pandemic except in highly connected countries, or in regions with low transmission that wanted to keep the virus out, says co-author Mark Jit, an infectious-disease modeller at the London School of Hygiene & Tropical Medicine. Preventing travel from high-prevalence countries would be sufficient to reduce exposure in many regions, says Jit.
“Countries shouldn’t instinctively say that, just because there is a pandemic, we should have travel restrictions.” Hoffman says that observational studies are now needed to tease out the effectiveness of countries completely shutting their borders. “There is a good chance that a whole lot of what we are doing is causing more harm than good.”