WHO reports on Omicron sublineage BA.2

Feb. 23, 2022

The World Health Organization’s (WHO) Technical Advisory Group on SARS-CoV-2 Virus Evolution said that countries should continue to monitor BA.2 as a sublineage of Omicron.

Omicron, a SARS-CoV-2 variant, is made up of several sublineages, including the most common ones: BA.1, BA.1.1 and BA.2.

The WHO said that BA.2 differs from BA.1 in its genetic sequence, including some amino acid differences in the spike protein and other proteins. While studies have shown that BA.2 has a growth advantage over BA.1, the WHO notes that “initial data suggest that BA.2 appears inherently more transmissible than BA.1, which currently remains the most common Omicron sublineage reported. This difference in transmissibility appears to be much smaller than, for example, the difference between BA.1 and Delta.”

The WHO also notes that case rates continue to decline globally. As of February 23, the total number of COVID-19 cases that have occurred during the pandemic was 427,927, 602, while deaths totaled 5,907,714, according to the Coronavirus Resource Center at Johns Hopkins University.

In the United States, COVID-19 cases and deaths have continued to decline over the past 30 days, according to the COVID data tracker at the Centers for Disease Control and Prevention (CDC). As of February 21, there have been 78,389,155 cases and 932,984 deaths in the United States.

Summarizing research comparing disease severity, the WHO said that preliminary laboratory data from Japan generated using animal models without any immunity to SARS-CoV-2 suggested that BA.2 may cause more severe disease in hamsters compared to BA.1. However, there was no reported difference in severity between BA.2 and BA.1 in real-world data from South Africa, the United Kingdom, and Denmark, where immunity from vaccination or natural infection is high.

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