Cases of Omicron in Gauteng, South Africa’s most populous province and home to its biggest city, Johannesburg, rose slightly from a seven-day daily average of 9,645 last Thursday, to 10,131 on Sunday. At the same time, the positivity rate of those being tested and the number of hospitalizations have both been falling. Data from the country’s National Institute for Communicable Diseases shows positivity rates dropping from 30% to around 15% between Thursday and Saturday, while the number of new hospitalizations fell from 207 to 64 over the same period.

“The positivity rate in South Africa has been flattening and now declined for the past two days,” Scott Gottlieb, a senior fellow for the American Enterprise Institute and former FDA commissioner, tweeted on Sunday.

This and other COVID data suggest that the infections from the COVID-19 mutation could peak during the next week before beginning to drop, says Pieter Streicher, a coronavirus analyst at the University of Johannesburg, who compared the wave of infections with case numbers from the Delta strain. “The peak is now likely to end up in the window specified,” he tweeted, marking out a period between last Friday, Dec. 10, and next Monday, Dec. 20.

Streicher says the continued, albeit slow, rise in average daily cases is “most likely” the result of a reporting delay, which saw 16,716 new Omicron cases reported on Sunday, Dec. 12.

This optimistic assessment is in contrast to the deep anxiety that Omicron has stoked in the U.S. and Europe, where policymakers worry that the variant might be the one scientists have dreaded since the start of the pandemic: a vaccine-resistant strain capable of infecting massive numbers of people. These worries may be overblown, at least in Streicher’s reading of the situation.

“A major fear in Europe seems to be the expectation that Omicron will infect up to 70% of the population,” Streicher tweeted. “Omicron will infect only 15 to 25% in South Africa, and we only have light restrictions (a curfew from 12-4am).”

In Omicron’s very short history, two features seem to have emerged: First, it spreads at wildfire speed. Second, it appears less deadly than COVID-19’s original strain—perhaps because 56% of the world has now received at least one dose of a coronavirus vaccine. A study last week of patients in the South African city of Tshwane showed that few COVID-19 patients needed ventilators, and of those that did, most had been admitted to the hospital for other health reasons.

Even so, it is the lightning pace of spread that worries governments, which fear the variant could quickly become dominant among COVID-19 cases.

U.K. Prime Minister Boris Johnson warned on Sunday that the country faced a “tidal wave” of Omicron infections, and on Monday he confirmed that at least one person had died of the variant. Infections in the U.K. are doubling in the country every two or three days, according to epidemiologist Neil Ferguson, who is on the government’s Scientific Advisory Group for Emergencies. The World Health Organization warned on Monday that Omicron spreads faster than the Delta variant, and that there were still few hard facts about whether it was less deadly. “It remains unclear to what extent Omicron may be inherently less virulent,” the WHO said.

But South Africa’s data shows Omicron has indeed been much less deadly there than previous COVID-19 strains—at least so far—even though only about 23% of the population is fully vaccinated.

“Even if peak daily case levels exceed Delta by a factor of three (34,000 per day), the number of patients ending up on ventilators will only peak at 140,” said Streicher, the University of Johannesburg analyst, adding his calculation is based on a 10-day lag between people being infected and then placed on ventilators.” The number, he says, “is extremely low.”

The U.S. and European Union imposed a travel ban on southern African countries within days of South Africa first reporting Omicron on Nov. 23—a move that those countries protested as unfairly punishing them for having revealed the new variant.