The global death toll surpassed 100,000, with more than 1.6 million confirmed cases.

President Trump called the question of when to relax social distancing guidelines “the biggest decision I’ll ever make.”

The World Health Organization will soon begin large-scale antibody testing in multiple countries.

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Restrictions may be around for a while

New federal projections show that stay-at-home orders, school closures and social distancing greatly reduce infections of the coronavirus. But if the restrictions are lifted after 30 days, experts say, it would lead to a drastic spike in cases.

For states like New York, Massachusetts and Illinois, which ordered restrictions in late March, that spike would come in mid- to late summer, according to the projections.

“It’s important to remember this is not the time to feel that, since we have made such important advance in the success of the mitigation, that we need to be pulling back at all,” Dr. Anthony Fauci, an infectious disease expert and member of the White House’s coronavirus task force, said on Friday.

The projections, which were prepared by the Departments of Homeland Security and Health and Human Services, offer a sobering argument for continued restrictions:

Without any mitigation, the projection says, the death toll from the coronavirus could have reached 300,000.

If officials lift stay-at-home orders after 30 days, the death total is estimated to reach 200,000 — even if schools remain closed, people work remotely and social distancing continues.

The restrictions must be lifted eventually, of course, and Dr. Fauci noted that an increase in cases would undoubtedly follow. But the new projections show how crucial the timing will be.