Omicron, also known as B.1.1.529, has three variants, BA.1, BA.2 and BA.3. Recently, a new coronavirus variant known as “Omicron’s sister” has been classified by the UK Health and Safety Executive as a “variant virus under investigation”. A new strain of coronavirus, known as “Omicron’s sister”, was recently classified as a “variant under investigation” by the UK Health and Safety Executive, namely the Omicron BA.2 variant. International data suggest that the BA.2 variant lacks a key mutation, which may make it more difficult to track, more transmissible, and more difficult to distinguish from other variants. although the BA.2 variant is easily transmissible, the severity of cases of BA.2 infection is comparable to that of infection with the original Omicron strain. Based on previously disclosed official data from South Africa and the UK, the proportion of asymptomatic infections with Omicron may be as high as 80-90%. Compared to the previous New Crown strain, the Omicron variant caused more asymptomatic and milder cases. That is, BA.2 may spread relatively faster, but is not necessarily more virulent than BA.1. In addition, the difference in vaccine effectiveness between BA.1 and BA.2 may also be small. Currently, all variants have the potential to cause severe illness or death, and although the BA.2 variant has not been classified as a “strain of concern” by the WHO, it does not mean that we can relax our vigilance. Prevention of virus transmission is always the key, and the new coronavirus vaccine remains effective in reducing severe illness and death. Individuals still need to take precautions by keeping at least 1 meter distance in public places, wearing a mask, opening windows, keeping hands clean, coughing or sneezing into elbows or tissues, getting vaccinated, and avoiding poorly ventilated or crowded areas.