New COVID-19 cases have fallen in South Africa after the country was the first to report that Omicron had become its dominant COVID variant, raising hopes that Omicron waves around the world may be shorter and less deadly than previous waves.

“All indicators suggest the country may have passed the peak of the fourth wave,” South Africa’s government said in a statement on Thursday. The government added that while the “highly transmissible” variant has spread rapidly throughout South Africa, hospitalization rates are lower than previous waves and the country has spare hospital capacity “even for routine health services.”

South Africa has averaged 10,324 COVID-19 new cases per day in the past week, less than half of the average of 23,000 cases per day seen during the country’s mid-December peak.

“The speed with which the Omicron driven fourth wave rose, peaked and then declined has been staggering… [This Omicron wave] was a flash flood more than a wave,” Fareed Abdullah, a director at the South African Medical Research Council, wrote on Twitter about Tshwane, the first city to document the Omicron variant.

Tulio de Oliveira, Director of South Africa’s Centre for Epidemic Response and Innovation, cautioned on Twitter that South Africa is not “out of the woods” yet, given that its test positivity rate is at 28%. The World Health Organization says outbreaks should only be considered under control if the test positivity rate is below 5%.

South Africa will maintain its mask mandate in public places and limit public gatherings to 1,000 people indoors or 2,000 people outdoors.

South Africa may provide some of the earliest indications of how Omicron waves may develop in the rest of the world, as more COVID-19 cases are reported globally than at any point in the pandemic. Infection rates are setting records in the U.S., Australia, and throughout Europe. In the U.S., where Omicron has likely become dominant, the government on Thursday reported over 580,000 new COVID-19 infections, shattering its own daily case record.

Yet, according to the U.S. Centers for Disease Control, COVID-19 hospitalization rates in the U.S. have not spiked to the same degree, creeping up 14% in the past week compared to a 60% jump in infections. But public health officials caution that hospitalization data can lag infections by at least two weeks, and doctors in Washington D.C. and other parts of the U.S. and are reporting that emergency rooms are being overwhelmed with COVID-19 patients.

U.S. CDC chief Dr. Rochelle Walensky said to the Associated Press on Wednesday that Omicron has been “mild” in almost all of the cases it has seen so far, but that the best defence against severe cases is getting a full vaccine regimen along with a booster shot.

Still, the World Health Organization and some public health experts warned this week about extrapolating data from South Africa and not to underestimate the threat of Omicron.

“I am highly concerned that Omicron, being more transmissible, circulating at the same time as Delta, is leading to a tsunami of cases,” WHO Director-General Tedros Adhanom Ghebreyesus said on Wednesday.

Mike Ryan, executive director of the WHO’s Health Emergencies Program, also warned Wednesday that South Africa’s population is younger than most other countries, which may make it difficult to determine if the variant is also less severe for older and more vulnerable populations. Ryan also noted that many South Africans had antibodies from previous COVID infections, which complicates efforts to determine whether Omicron is less likely to cause severe disease.

But even if it remains unclear whether South Africa’s Omicron wave may indicate how the disease spreads elsewhere, there is evidence that suggests getting an Omicron infection may provide some protection against Delta. A study by the Africa Health Research Institute this week found that those infected with Omicron had a fourfold increase in protection levels against getting infected with Delta two weeks after initially getting sick.

The authors said the study suggested that while Omicron will likely outpace Delta as the globally dominant strain, that might be good news if Omicron eventually proves to be less severe.

“The incidence of COVID-19 severe disease would be reduced and the infection may shift to become less disruptive to individuals and society,” the scientists wrote.