People hospitalized with the omicron variant of COVID-19 tend to be in the hospital a shorter period of time, have less need for supplemental oxygen and generally don't progress as frequently to severe disease, according to a new South African study released Thursday.
The study, which has not yet been peer-reviewed or accepted for publication, is one of the most comprehensive looks yet at what happens to people once they progress past omicron infection to hospitalization - and while early and tentative, the news does appear to be somewhat optimistic.
The authors, from some of South Africa's top schools and research institutions, compared outcomes in Gauteng province in South Africa for the first four weeks of the omicron wave, compared to the first four weeks of the waves caused by the beta and delta variants in late 2020 and mid-2021.
While new infections were astronomically higher with omicron than beta or delta, the percentage of those hospitalized was far lower -- just 4.9%, almost 10 percentage points lower than the delta wave.
COVID-19 omicron variant analyzed
For those who were hospitalized, outcomes also appeared to be better. Less than 30% of those with omicron met the local criteria for severe disease, half of the prior variants. Less than 20% required supplemental oxygen, half of the prior waves. And the median hospital stay with omicron was just 4 days, versus 7-8 days in the prior waves.
"During the first four weeks of the Omicron-dominated fourth wave, the proportion of patients requiring hospital admission was substantially lower and those admitted had less severe illness, with fewer requiring oxygen, mechanical ventilation and intensive care compared to the first four weeks of the Beta- or Delta-dominated waves in Gauteng Province in South Africa," the authors wrote. "In-hospital case fatality ratios were over 4-fold lower during the Omicron-dominated wave compared to either the Beta- or Delta-dominated waves."
The authors cautioned that their results were preliminary, that they excluded about a third of the early omicron hospitalizations where outcomes were not yet known, and that impacts could differ in other places based on infection and vaccination history.
Omicron in kids vs adults
They also found some striking differences in younger patients versus adults. Among those under age 20, the percentage of those infected who were admitted to hospitals was sharply higher with omicron than with the delta wave.
The percentage of hospitalized patients who died was slightly lower, but because so many more were infected, the actual death toll was higher. The authors said this may be due to lower rates of prior infection or vaccination in kids than adults, at least locally.