More COVID-19 cases have been reported to the World Health Organization (WHO) in the last 24 hours than on any day since the pandemic began, the WHO’s Director-General Tedros Adhanom Ghebreyesus said Wednesday.

Nearly 4.8 million cases have been reported worldwide since the virus was first detected in Wuhan, China, late last year.

Though Ghebreyesus said during a Wednesday news conference that nearly two-thirds of the new cases were reported in just four countries, he said the WHO was especially concerned about rising case counts in low-income regions of the world.

“In the last 24 hours, there have been 106,000 cases reported to WHO –- the most in a single day since the outbreak began,” Ghebreyesus said.

“We’re very concerned about the rising numbers of cases in low- and middle-income countries.”

The record report came as many of the world’s wealthier countries were preparing to lift restrictions imposed on residents to prevent further spread of the virus. In the U.S., several states have begun easing lockdown restrictions over the last few weeks, despite persisting high case counts around the country. According to recent situation reports published by the WHO, the U.S. reported 45,251 new cases on Tuesday alone.

The U.S. surpassed China as the country with the most COVID-19 cases by the end of March and has kept its top position ever since, with more than 1.5 million cases confirmed nationwide by Wednesday morning. Russia and Brazil, which hold the second- and third-place positions in terms of country case counts, also reported thousands of new cases to the WHO over the last few days.