COVID-19 testing has dropped as much as 90% worldwide, making it tougher for scientists to spot new variants

Testing for COVID-19 has plummeted across the globe, making it much tougher for scientists to track the course of the pandemic and spot new, worrisome viral mutants as they emerge and spread.

Experts say testing has dropped by 70 to 90% worldwide from the first to the second quarter of this year—the opposite of what they say should be happening with new Omicron variants on the rise in places such as the United States and South Africa.

“We’re not testing anywhere near where we might need to,” said Dr. Krishna...