Greek Alphabet letters that have been used up till now for COVID

Keeping up to date with Greek Variants of concern:

Alpha, Beta, Gamma, Delta, Omicron Variants of interest:

Lambda, Mu Former variants of interest: Epsilon, Zeta, Eta, Theta, Iota, Kappa

Skipped letters: Nu & Xi

Available : Pi, Rho, Sigma, Tau, Upsilon, Phi, Chi, Psi, Omega