Early assessment of the clinical severity of the SARS-CoV-2 Omicron variant in South Africa | medRxiv
Today we got some encouraging results from researchers in South Africa who published a study (which is not yet peer-reviewed) suggesting that people diagnosed with Omicron in South Africa in October & November were 80% less likely to be admitted to hospital than those diagnosed with a Delta infection during the same period. People hospitalized with Omicron infections were 70% less likely to develop severe disease than those admitted with Delta between April and November. The team controlled for age and other risk factors known to put folks at higher risk for hospitalization. From the report:
When compared to non-SGTF (Alpha & Delta) infections, we found that SGTF (Omicron) infections had an 80% lower odds being admitted to hospital, but did not differ in the risk of severe disease among hospitalised individuals. When compared to Delta infections, SGTF (Omicron) infections were associated with a 70% lower odds of severe disease.
Before doing handstands… consider that the levels of immunity in the population from previous infections and vaccinations is likely a big reason for the reduced severity they observed. As the authors state in their report, “It is difficult to disentangle the relative contribution of high levels of previous population immunity versus intrinsic lower virulence to the observed lower disease severity.”
Incomplete vaccination data, and the fact that the majority of re-infections were likely not detected,
resulted in incomplete adjustment for the effect of prior immunity in our analyses.
To get a picture of the level of community immunity that exists in South Africa, consider that an estimated 60% to 70% of people in South Africa have had a prior COVID-19 infection. In terms of vaccination status, 58% of individuals aged ≥60 years, 55% aged 50-59 years, 43% aged 35-49 and 24% aged 18-34 years are fully vaccinated there (one dose of J&J or two doses of Pfizer-BioNTech or AztraZeneca). Because Delta infections happened earlier that the Omicron infections, community immunity was higher during the Omicron era.
There are many limitations in the study outlined by the authors and the results may be different in the U.S., but this is at least somewhat encouraging.
Remember, Omicron is at least twice as contagious as Delta and evades some of the immunity built via infections and the vaccines. That means that even if Omicron infections really are 80% less likely to require hospitalization vs Delta infections, we’ll still have an influx into our already overwhelmed hospitals because of the sheer number of infections that are on the way because of the complete absence of mitigation in Arizona (except in Pima County) and the greatly increased transmissibility of Omicron.
Meanwhile, Governor Ducey & Interim ADHS Director Herrington are MIA.