After the omicron variant sent reports of new coronavirus cases skyrocketing to record levels in South Africa, case counts have now started falling and are down by more than 20% in the last week, researchers in the country said.

“This is encouraging and quite optimistic in terms of the decreasing trends and case numbers,” said Dr. Michelle Groome, an epidemiologist at the National Institute of Communicable Diseases.

She cautioned, however, that the case figures may have been distorted somewhat by reduced testing during the holiday season.

In the epicenter of South Africa’s latest outbreak, Gauteng province, new infections seem to have peaked in the last week, Groome said. While the densely populated province — home to Johannesburg and the capital, Pretoria — was still accounting for more than one-quarter of the country’s new cases over the past week, they were down by nearly half from the week before.

Three more of South Africa’s nine provinces also reported decreases.

The country’s coastal provinces, including KwaZulu-Natal, are still reporting increases in new cases, officials said.

The omicron variant is dominant in South Africa, appearing in 95% of all new positive test samples that are being genetically sequenced.

Studies based on early data from Gauteng province suggest that COVID-19 cases caused by omicron tend to be less severe than those associated with earlier variants. In the first four weeks of the omicron wave, 5.7% of new cases were admitted to the hospital, compared with 15.6% in the delta wave and 16.2% in the beta wave.

There was also a “downward trend” in patients needing critical care and in deaths from COVID-19, said Dr. Waasila Jassat, a public health specialist at the institute.

However, the population of Gauteng is more heavily vaccinated than other parts of the country, and a high proportion of people there have some level of immunity, either from vaccination or prior infections. Researchers caution that the virus may behave differently in other populations.

The data is welcome news in South Africa, where many people have been bracing for new lockdown restrictions as Christmas and New Year’s Day approached. The South African government has maintained a midnight-to-4 a.m. curfew and has discouraged large holiday gatherings but has not reimposed the kinds of strictures it used early in the pandemic, like limits on alcohol and tobacco sales.

More than 44% of the country’s adult population has been fully vaccinated, but the daily pace of new vaccinations has fallen short of the government’s goals.

The holiday season — the start of summer in the Southern Hemisphere — is a time when many thousands of South Africans travel to the countryside or crowd the beaches, and it is a popular time to marry. Weddings in particular could turn into “superspreader events,” the health ministry warned.

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This article originally appeared in The New York Times.