South Africa was where the new Omicron variant was first identified, and cases there have taken off rapidly.
This is starting to be seen in other countries, and the World Health Organization (WHO) says it is “spreading at a rate we have not seen with any previous variant”.
What else can we learn from the South African experience?
Does Omicron cause milder disease?
Data on hospital admissions for Covid in South Africa show them rising quite sharply in all provinces.
But they are not going up as fast as you would expect given the number of cases. Fewer patients currently need oxygen and ventilators, and they are in hospital for shorter periods.
Discovery Health, a major health provider there, calculated adults infected early in the Omicron outbreak were roughly 30% less likely to be admitted to hospital than those infected in South Africa’s first wave.
Senior South African scientists say this doesn’t show the variant itself is milder, though.
The big difference from previous waves is the rate of vaccination and natural immunity in the population.
Although either two doses of vaccine or a previous infection appear much less effective at stopping people catching the Omicron variant, they still seem to provide protection against severe illness.
Dr Vicky Baillie, a senior scientist at Chris Hani Baragwanath hospital in Johannesburg, said the lower rates of hospital treatment were probably because of people having greater immunity
“There’s no evidence it’s a less virulent mutation,” she said.