News Navigator: How are COVID-19 variants named, and what's the situation in Japan?

The Mainichi Shimbun answers some common questions readers may have about the situation surrounding variant COVID-19 strains and the names they are given by the World Health Organization (WHO).

Question: While the number of coronavirus patients is significantly decreasing in Japan, what strains are spreading overseas?

Answer: There are many mutant COVID-19 strains, but the WHO designated the alpha, beta, gamma and delta strains as variants of concern (VOCs) -- posing a risk of increased transmissibility and more serious symptoms. The number of VOCs has not changed since mid-May.

Furthermore, the WHO is monitoring the lambda and mu strains closely as variants of interest (VOIs).

Q: What are the characteristics of the lambda and mu strains?

A: The lambda strain was confirmed in Japan for the first time in July during airport checks. Although it contains a mutation that may increase its transmissibility, the National Institute of Infectious Diseases considers the risk of the variant spreading domestically to be extremely low. Meanwhile, the mu strain contains a mutation that makes it more infectious and able to dodge antibodies. The WHO has said that it may adversely affect coronavirus vaccine effectiveness.

Q: Are letters from the Greek alphabet used to name all the variants?

A: Yes. The WHO has been labeling VOCs and VOIs with Greek letters since the end of May. In addition to the six current key mutant stains, variants that have been designated as VOIs in the past and are currently excluded were dubbed kappa, iota, eta, epsilon, zeta and theta.

Q: What if they run out of letters?

A: As of Oct. 12, half of the 24-letter Greek alphabet have already been used. According to the online version of The Telegraph, a British daily, the WHO is considering using the names of constellations if they run out of Greek letters.

(Japanese original by Naomi Hayashi, Lifestyle and Medical News Department)