WHO provides update on Omicron variant

The World Health Organization (WHO) has released an update on the Omicron (B.1.1529) coronavirus variant, which it designated a Variant of Concern on November 26, 2021. The decision, based on advice from WHO's Technical Advisory Group on Virus Evolution (TAG-VE), stems from evidence suggesting Omicron possesses several mutations that could impact its behavior, such as its spread and the severity of illness it causes.

Researchers in South Africa and globally are conducting studies to better understand Omicron. It remains unclear whether Omicron is more transmissible than other variants, including Delta. While reported cases have increased in affected South African regions, epidemiological studies are underway to determine if this is due to Omicron or other factors. Similarly, it is not yet clear if Omicron causes more severe disease. Preliminary data indicates rising hospitalization rates in South Africa, but this may be attributed to an overall increase in infections rather than a specific effect of Omicron.

Preliminary evidence suggests an increased risk of reinfection with Omicron compared to other variants, though information is limited. WHO is collaborating with technical partners to assess the potential impact of this variant on countermeasures, including vaccines. Current vaccines, however, continue to be critical in reducing severe disease and death, including against the dominant Delta variant. Widely used PCR tests continue to detect infections, including those caused by Omicron. Treatments such as corticosteroids are still being evaluated for effectiveness in managing severe cases.

WHO is coordinating extensive global research to rapidly assess Omicron, including its transmissibility, disease severity, the performance of vaccines and diagnostics, and treatment efficacy. The organization urges countries to enhance surveillance and sequencing, share genome sequences, report cases, and conduct field investigations to understand any differences in transmission or disease characteristics. Countries are also advised to continue implementing effective public health measures to reduce overall COVID-19 circulation and strengthen preparedness for increased case numbers.