It has added BA.4 and BA.5, sister variants of the original BA.1 Omicron variant, to its watchlist. It already tracks BA.1 and BA.2 – now globally dominant – as well as BA.1.1 and BA.3.
Read more: Risk of re-infection: Omicron appears to produce shorter immunity, experts say
The WHO said it had begun monitoring them because of “additional mutations that need to be further studied to understand their impact on the immune system’s escape potential”. Viruses are constantly mutating, but only certain mutations affect their ability to spread or prevent previous immunity from vaccination or infection or the severity of the disease they cause. The story goes on under the ad For example, BA.2 now accounts for almost 94 percent of all sequence cases and is more contagious than its siblings, but evidence to date suggests it is less likely to cause serious illness. Trending Stories
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Only a few dozen cases of BA.4 and BA.5 have been reported in the global GISAID database, according to the WHO. The UK Health and Safety Administration said last week that BA.4 had been found in South Africa, Denmark, Botswana, Scotland and England from January 10 to March 30. 1:52 Vaccinated Canadians May Have COVID-19 Symptoms Even If the Test Is Negative Vaccinated Canadians May Have COVID-19 Symptoms Even If the Test Is Negative All BA.5 cases have been in South Africa since last week, but on Monday the Botswana Ministry of Health said it had identified four cases of BA.4 and BA.5, all between 30 and 50-year-olds who had been fully vaccinated and showed mild symptoms. The story goes on under the ad (Report by Jennifer Rigby, additional by Brian Benza in Gaborone; Edited by Josephine Mason and Hugh Lawson)
