Covid Characters

The Friday File: At present there are five Covid-19 variants of concern: alpha, beta, gamma, delta and omicron. There are two variants of interest: lambda and mu, and three former variants of interest now classified as variants under monitoring: kappa, iota, and eta. There are also three former variants: epsilon, theta, and zeta. Importantly, nu and xi were deliberately skipped. Only nine Greek letters remain! Then what?? Pi is next.