The BA.2 virus -- a subvariant of the Omicron coronavirus variant -- isn't just spreading faster than its distant cousin, it may also cause more severe disease and appears capable of thwarting some of the key weapons we have against Covid-19, new research suggests.
New lab experiments from Japan show that BA.2 may have features that make it as capable of causing serious illness as older variants of Covid-19, including Delta.
And like Omicron, it appears to largely escape the immunity created by vaccines. A booster shot restores protection, making illness after infection about 74% less likely.