Even as the US grapples with its most recent wave of Covid-19, new research suggests that variants on the horizon may keep case levels high.
The next influx of infections will probably come from the newer Omicron subvariants BA.4 and BA.5, two closely related viruses that were first characterized in South Africa and that landed in the United States around late March.
These variants are gaining ground against BA.2, particularly in the central part of the country. Recent research suggests that they escape immunity created by vaccines and past infections.
