Covid: Omicron causing fewer hospitalisations than delta, early data from South Africa suggests

People in South Africa infected with the omicron variant of Covid are being hospitalised less often than those with earlier versions of the disease such as delta, an early study suggests.

Initial findings from South Africa, which are so far based on just three weeks of data, suggest that while omicron is more infectious than previous variants, people with it are around a third as likely to end up in hospital than those with delta.

This could mean that some of the effects of greater transmissibility are offset by a lower chance of severe illness.

The study – published by Discovery Health, a healthcare provider responsible for 3.7 million patients in South Africa – also shows that vaccines are not as effective against omicron, which poses a higher risk of “breakthrough infections”.

Epidemiologists have warned that data from a few more weeks is needed to corroborate these preliminary conclusions, especially considering the average age of people involved in the study is 34 – and younger people generally tend to have mild symptoms.

However, the report’s conclusions do appear to mirror that of real-life datasets in other regions. In the UK, for instance, just 10 people are known to have been admitted to hospital with omicron so far, despite the variant first being detected here almost three weeks ago.

A comparison of the first three weeks of some Covid variants’ spread in South Africa shows a stark difference in admissions. For every 1,000 infections in the country, there were 131 beta hospitalisations, 101 delta admissions and just 38 omicron admissions.

However, Dr Ryan Noach, the chief executive of Discovery Health, said he and others “remain concerned that health systems could still be overrun, frankly, because of the sheer volume of cases” caused by omicron.

He told reporters: “This is clearly a highly contagious variant, [but] what’s encouraging at this stage is a flatter trajectory of hospital admissions, indicating a likely lower severity of the illness.”

Asked by The New York Times about the most effective way to protect against omicron, Dr Noach advised “hybrid immunity” – meaning vaccinations, including for those who previously contracted the virus, alongside all non-pharmaceutical precautions against Covid, such as wearing a face mask and social distancing.

The study found that people who were infected with delta had a 40 per cent relative risk of contracting the omicron variant, while those infected with the beta variant at the beginning of last year faced a 60 per cent chance of reinfection with omicron.

Elsewhere, it was concluded that the Pfizer-BioNTech vaccine’s efficacy seemed to wane in the face of omicron, decreasing immunity to just 33 per cent compared with 80 per cent in September and October after the delta wave had subsided.

Still, Pfizer’s ability to curb severe illness and hospitalisation from omicron was around 70 per cent after two doses, the study found.

“Omicron has materially reduced vaccine effectiveness against new infections, potentially compounded by waning durability,” the authors concluded. And while Covid booster jabs increased the vaccine’s efficacy against infection, few doses are available in South Africa, they added.