EYECARE: Coronavirus BRIEFING: The Latest COVID-19 Data What to Know About the Mu Variant By Staff Wednesday, September 15, 2021 12:21 PM It seems like new COVID-19 variants are popping up every day, but according to WebMD, "only four so far have raised enough alarm to warrant a World Health Organization 'variant of concern' designation—Alpha, Beta, Gamma, and Delta." Most recently, the Mu variant has appeared, and the WHO has classified it as a "variant of interest." Head over to WebMD to learn what we know so far about the Mu variant.