South Africa's Omicron Data Shows COVID Reinfection Rate Higher Than Other Variants

According to new data from South Africa, early reports suggest the rate at which people are reinfected with coronavirus is higher with the Omicron variant than other COVID-19 variants.

Willem Hanekom, the director for the African Health Research Institute, said that people who previously had COVID-19 and are being reinfected with the virus is happening at a much higher rate with Omicron.

Hanekom said early data shows that Omicron is slightly escaping immunity based on the higher rate of reinfection. The data also shows that younger people, primarily those who are unvaccinated, are becoming infected more often by Omicron, Hanekom said.

The Omicron variant is spreading quickly in South Africa. Over the weekend, the nation reported more than 16,000 new cases per day. In mid-November, it reported fewer than 200 new cases per day.

Dr. Jacob Lemieux, who monitors the variants for a research collaboration led by Harvard Medical school, said that although it's still early, "data is starting to trickle in, suggesting that Omicron is likely to outcompete Delta in many, if not all, places."

"The virus is spreading extraordinarily fast," Hanekom said. "It's likely to become the dominant strain in the coming weeks and months and will likely cause a surge in case numbers."

Some scientists, analyzing data from South Africa and the United Kingdom, suggest Omicron could emerge the victor.

But others said Monday it's too soon to know how likely it is that Omicron will spread more efficiently than Delta, or, if it does, how fast it might take over.

"Especially here in the U.S., where we're seeing significant surges in Delta, whether Omicron's going to replace it I think we'll know in about two weeks," said Matthew Binnicker, director of clinical virology at Mayo Clinic in Rochester, Minnesota.

Many critical questions about Omicron remain unanswered, including whether the virus causes milder or more severe illness and how much it might evade immunity from past COVID-19 illness or vaccines.

On the issue of spread, scientists point to what's happening in South Africa, where omicron was first detected. Omicron's speed in infecting people and achieving near dominance in South Africa has health experts worried that the country is at the start of a new wave that may come to overwhelm hospitals.

Omicron accounts for more than 90 percent of the new cases in Gauteng province, the epicenter of the new wave, according to experts. The new variant is rapidly spreading and achieving dominance in South Africa's eight other provinces.

"If you look at the slopes of this wave that we're in at the moment, it's a much steeper slope than the first three waves that South Africa experienced. This indicates that it's spreading fast and it may therefore be a very transmissible virus."

But Hanekom, who is also co-chair the South African COVID-19 Variants Research Consortium, said South Africa had such low numbers of Delta cases when Omicron emerged, "I don't think we can say" it outcompeted Delta.

Scientists say it's unclear whether omicron will behave the same way in other countries as it has in South Africa. Lemieux said there are already some hints about how it may behave; in places like the United Kingdom, which does a lot of genomic sequencing, he said, "we're seeing what appears to be a signal of exponential increase of Omicron over Delta."

In the United States, as in the rest of the world, "there's still a lot of uncertainty," he said. "But when you put the early data together, you start to see a consistent picture emerge: that Omicron is already here, and based on what we've observed in South Africa, it's likely to become the dominant strain in the coming weeks and months and will likely cause a surge in case numbers."

But Binnicker said things could play out differently in other parts of the world or in different groups of patients. "It'll be really interesting to see what happens when more infections potentially occur in older adults or those with underlying health conditions," he said. "What's the outcome in those patients?"

As the world waits for answers, scientists suggest people do all they can to protect themselves.

"We want to make sure that people have as much immunity from vaccination as possible. So if people are not vaccinated they should get vaccinated," Lemieux said. "If people are eligible for boosters, they should get boosters, and then do all the other things that we know are effective for reducing transmission—masking and social distancing and avoiding large indoor gatherings, particularly without masks."

The Associated Press contributed to this report.