Unvaccinated people infected with the Omicron variant are less likely to fall seriously ill, require hospitalization or die compared to the previous COVID-19 variants, a South African study showed on Friday.
The study, led by the National Institute of Communicable Diseases in the Western Cape region, compared 11,609 patients from the first three COVID-19 waves with 5,144 patients from the new Omicron-driven wave.
It found that 8 percent of patients were hospitalized or died within 14 days of testing positive for COVID during the Omicron wave — compared to the 16.5 percent in the first three waves.
“After adjusting for age, sex, comorbidities and subdistrict there was a substantially reduced hazard of death in wave four compared to wave three,” the study said.
“The extent of reduction was attenuated when additionally considering prior diagnosed infections and vaccination.”
Even after prior COVID infections were taken into account, the study found there was roughly a 25 percent reduction in severe hospitalization or death with Omicron than the Delta variant.
Public health experts have already said Omicron appears to cause less severe disease than other variants, including Delta.
But scientists have been trying to determine whether the less severe symptoms are because people are now vaccinated or have already had COVID, or if Omicron is naturally more mild.
The study, which is yet to be peer-reviewed, found about a quarter of the reduced risk of severe disease with Omicron was attributable to characteristics of the virus itself.
“In the Omicron-driven wave, severe COVID-19 outcomes were reduced mostly due to protection conferred by prior infection and/or vaccination, but intrinsically reduced virulence may account for an approximately 25 percent reduced risk of severe hospitalization or death compared to Delta,” researchers said.
Data out of South Africa, which is where the Omicron variant was first detected, has shown lower hospitalization and death rates in this latest wave.
Only 27 percent of South Africa’s population are fully vaccinated against COVID-19.
The South African study echoes one released by the US Centers for Disease Control and Prevention earlier this week that Omicron poses a “substantially reduced risk” of serious illness compared to Delta.
The US-backed study found Omicron is more than 90 percent less likely to kill those infected with the virus.