The World Health Organization is currently monitoring dozens of cases of two additional sub-variants of the highly portable Omarron strain of SARS-CoV-2 to determine whether they are more infectious or dangerous.
On Monday, the WHO announced that it had added BA.4 and BA.5 to its watch list. The organization is already following other members of the Omicron family, including BA.1 and BA.2 – the sub-option that now dominates the world – as well as BA.1.1 and BA.3.
The WHO said it had begun tracking them because of their “additional mutations that need to be further studied to understand their impact on the potential for escape immunity.”
Viruses mutate all the time, but only a few mutations affect their ability to spread or avoid previous immunity from vaccination or infection, or the severity of the disease they cause.
For example, BA.2 now accounts for almost 94 percent of all sequenced cases and is more transmissible than its siblings, but evidence so far shows that it is less likely to cause serious illness.
Only a few dozen cases of BA.4 and BA.5 have been reported in the global GISAID database, according to the WHO.
BA.4 cases found in many countries
The UK Health Security Agency announced last week that BA.4 had been found in South Africa, Denmark, Botswana, Scotland and England from January 10th to March 30th.
All BA.5 cases have been in South Africa since last week, but the Botswana Ministry of Health said on Monday it had identified four cases of BA.4 and BA.5, all among people aged 30 to 50 who have been fully vaccinated and are mild. symptoms.
Despite the increase in the percentage of genomes, BA.4 and BA.5 are still not causing a jump in infections in South Africa and further evolution of the Omicron variant is expected, said Tulio de Oliveira, director of the Center for Epidemic Response & Innovation in South Africa in a series of posts on Monday shared on Twitter.
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