In the past year, the rapid mutation of the coronavirus has triggered new variants, which have swept across the world: Delta last summer, then omicron in winter and more recently omicron’s subvariants BA.2, BA.4 and BA.5. The last pair have quickly become the world’s dominant forms of the coronavirus, as recorded in the GISAID international repository of coronavirus genetic sequences analyzed by The Washington Post. The worldwide chart of coronavirus variants below shows the sequence of omicron subvariants that have emerged since the peak of the delta wave in September 2021. The BA.4/BA.5 subvariants, which are very similar, were a small share just a few months ago and are now dominant.

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