The World Health Organization on April 11 said it is monitoring two new "sister variants" of the original omicron strain dubbed BA.4 and BA.5, according to global news network WION.
Four things to know:
1. Scientists are still working to determine the transmissibility and potential for severe disease from the strains, which share many of the same mutations as the omicron subvariant BA.2.
2. The first BA.4 sample was detected Jan. 10 in South Africa. Since then, the country has confirmed 41 cases, according to an April 8 report from the U.K. Health Security Agency.
3. Denmark has reported three cases, Botswana has identified two, and England and Scotland have each reported one case.
"Although the number of total genomes is small, the apparent geographic spread suggests that the variant is transmitting successfully," the U.K. Health Security Agency said.
4. The BA.5 strain was also detected in South Africa, with the earliest known sample reported Feb. 25. As of March 25, the country had confirmed 27 BA.5 cases.