On April 25, the Shandong province held a press conference on the prevention and control of the epidemic in Yantai City.
They announced that the 16 COVID cases analyzed belong to the same transmission chain. Genetic sequencing analysis reveals that those cases mentioned above were infected with a new variant, Omicron BA.2.3. This is the first time the strain has been found on the mainland.
Vice-Mayor Shen Jian said at the press conference that the new outbreak has features of spatial clustering, and the virus might have been spreading for days.
According to the report, the current outbreak in Yantai City began on April 22. Since then, the number of COVID-19 infections has increased rapidly in just two days.
On April 24, Yantai City registered 36 new infections, including two confirmed cases and 34 asymptomatic infections.
Vice Mayor of Yantai City Shen Jian added that the city has traced over 4,800 close contacts. Those people are now under quarantine.
Wang Guiqiang, a member of the Party Committee of the Yantai Centre for Disease Control and Prevention, said that the outbreak was caused by the BA.2 mutant strain of Omicron. It is more contagious and has a shorter incubation period.
The Italian news agency Ansa reported on April 13 that Massimo Zollo, geneticist, and Naples university COVID task force coordinator, explained that the BA.2.3 is derived from the BA.2 sub-variant and BA.1. However, BA.2.3 has more mutations compared to BA.2.