The virus is the summer house guest from hell. Any remaining hope that the coronavirus that’s pushed the U.S., Europe and much of Asia into historic economic downturns would take a holiday was all but crushed this week. The virus continues to rampage through parts of the U.S. and engulf nations across the developing world, particularly India, Brazil and South Africa. It’s made a comeback in Japan as well as areas of Europe and China.

The time until the release of a safe and effective vaccine will be very challenging, with countries like the U.S. and Brazil potentially leading the way in severity, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. The same type of surge in daily cases that took place in the U.S. around the Memorial Day holiday could be repeated around Labor Day, when schools reopen, he said.

“I think we’ll see a substantial increase in transmission that’s going to spill over into more adults and at-risk people,” he said. “And then that gets us into the beginning of flu season, when transmission is potentially enhanced by all the indoor activity. If you add that all up together it’s not a pretty picture.”

At the same time, as governments face new flare-ups and reimpose full or partial lockdowns, the prospects for a brisk global economic rebound later in the year have dimmed, according to economists and executives.

While the virus-stricken world is in a better place than in April and May, when near-total lockdowns to prevent virus spread delivered a savage economic hit, the continuing emergence of new hotspots, or sudden outbreaks in old ones, has disrupted economic activity just enough to slow momentum toward a robust recovery.

Awaiting Vaccine

High-frequency data that track indicators such as restaurant bookings and job postings have been flat or trended downward in some economies. The highly transmissible virus is expected to remain a formidable and elusive adversary until a first generation of effective vaccines can be rolled out to the public, which many experts expect in 2021.

On Thursday, the U.S. announced that its economy contracted at a 32.9% pace from April through June, one of the biggest drops on record. As bad as that was, it was already baked into market expectations.