BA.4 and BA.5 Omicron Covid: How worried should we be?
Two new fast-spreading subvariants of Omicron are causing fresh surges of Covid around the world.
BA.4 and BA.5 were first identified in South Africa and may soon become the dominant strains in Europe and the US, health experts say.
What exactly are BA.4 and BA.5?
Ever since it first emerged, Covid has been mutating or shape-shifting. The new genetic versions that keep appearing are called variants.
There have been a few major variants already, such as alpha and delta, that have caused massive waves of infection.
The latest ones experts are concerned about – BA.4 and BA.5 – are very closely related to the Omicron variant behind last winter’s wave.
They were added to the World Health Organization’s monitoring list in March and have also been designated as variants of concern in Europe.
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