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.

Chart showing the third and fourth waves in South Africa
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 from 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.

Early data suggests Omicron leads to fewer hospital admissions than in previous waves
The WHO warns that the data suggesting the variant could be milder could also be skewed by the fact that numbers in hospitals are small, and most of those admitted are under the age of 40 – so at lower risk of falling seriously ill.

They may be in hospital for other reasons – but South African hospitals test everyone who is admitted, so pick up a lot of mild cases.

It could also be because over-60s in South Africa are much more likely than the average population there to be vaccinated, protecting them against severe disease.

And South Africa has a young population, with a median age of 27.6 years compared with 40.4 in the UK for example – so its experience of Omicron may not be the same as countries with older populations. Are more children getting?

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