Two years into the coronavirus pandemic, Americans can be forgiven if they’ve lost track of the latest variants circulating nationally and around the world. We’ve heard of the alpha, beta, gamma, delta, and omicron variants, but a new Greek-letter variant hasn’t come onto the scene in almost half a year.
Instead, a seemingly endless stream of “subvariants” of omicron, the most recent Greek-letter variant, has emerged in the past few months.
How different are these subvariants from one another? Can infection by one subvariant protect someone from infection by another subvariant? And how well are the existing coronavirus vaccines — which were developed before omicron’s emergence — doing against the subvariants?
We asked medical and epidemiological experts these and other questions. Here’s a rundown.
Q: What are the subvariants? How much do they differ from one another?
The omicron subvariants seem like an alphabet soup of letters and numbers. The original omicron variant was called B.1.1.529. The initial omicron variant begat such subvariants as BA.1; BA.1.1; BA.2; BA.2.12.1; BA.3; and the most recent, BA.4 and BA.5.
“They all differ from each other by having different mutations in the spike protein,” which is the part of the virus that penetrates host cells and causes infection, said Dr. Monica Gandhi, a professor of medicine at the University of California-San Francisco.
The minor-to-modest mutations in these subvariants can make them marginally more transmissible from person to person. Generally, the higher the number following “BA” in the subvariant’s name, the more transmissible that subvariant is. For instance, BA.2 is thought to be abou …