The omicron variant of COVID-19 has shown signs of being less virulent than other strains, with early hospital data out of South Africa indicating that patients infected with the variant require less intensive care.

Researchers at Steve Biko/Tshwane District Hospital Complex, a major hospital complex in Pretoria, South Africa’s capital and the center of the omicron outbreak, reported last week that the majority of patients in the COVID-19 ward there were asymptomatic. Their findings reflect similar trends at hospitals across the province as a whole, leading some infectious disease experts to be cautiously optimistic that omicron may manifest in a milder form of illness.


The analysis of 42 patients in the hospital’s COVID-19 ward found that only nine needed supplemental oxygen. Most of those patients were being treated for conditions other than COVID-19 but were found to be positive for the virus because of the hospital’s mandatory testing for new admissions. The average length of stay in the hospital over the past two weeks was about 2.8 days, far lower than the average 8.5 days for the past 18 months.

Dr. Anthony Fauci, the chief medical adviser to President Joe Biden, said on Sunday that “thus far, the signals are a bit encouraging.” Most of the patients who developed COVID-19 pneumonia at Steve Biko/Tshwane District Hospital Complex were unvaccinated, leading to hopes that the strain will not evade the protection given by vaccination.

The Pretoria doctors behind the report said that more time and study are required to fully answer the questions about the severity of the new omicron variant.

Scientists in the province have also speculated about whether the relatively low number of severe cases is due to greater overall population immunity. Large swaths of the population have been exposed to COVID-19 over the past two years.


Though omicron itself may be less virulent than the highly transmissible delta strain, it appears to be highly transmissible due to the dozens of mutations on the virus’s spike protein, which latch on to healthy cells to cause infection. The strain has been detected in at least 50 countries and 19 U.S. states since it was first found in California a week ago. The Biden administration said Tuesday that it expects the number of states that identify the variant to increase.

A more complete picture of the strain’s virulence will not become available for another couple of weeks due to the lag between detection of infection and hospitalization.

In the absence of more conclusive data on the variant’s virulence, the Biden administration moved swiftly last week to restrict travel from eight African countries at the center of the omicron outbreak, including South Africa. Administration officials have also pressed people to get a booster dose of a vaccine if eligible.