The BA.2.3 Omicron subvariant detected in Yantai, Shandong province, was likely introduced into the Chinese mainland from overseas, but it will have limited impact on China's epidemic control situation, experts said.

On Monday, the Yantai government said it had detected the Omicron BA.2.3 strain in its local cases. It is the first time that this variant has been seen on the Chinese mainland, leading to public speculation and concern on Chinese social media.

The city recorded 27 asymptomatic carriers on Sunday. Four confirmed cases and 107 asymptomatic infections have been logged in the recent outbreak, according to Yantai's health commission.

On April 13, Italian scientists reported that BA.2.3 contributed to around 20 percent of COVID-19 cases in the country. This strain has also been found circulating in Denmark, Japan, the Philippines and other parts of the world, according to the World Health Organization.

A Beijing microbiologist who requested anonymity said although the BA.2.3 strain has more mutations than its BA.2 ancestor, its mutations have little significance and therefore this strain is less noteworthy compared to the BA.2.12.1 subvariant that is gaining a foothold in the United States and India.

Last week, the US Centers for Disease Control and Prevention said BA.2 and BA.2.12.1 strains accounted for an estimated 93 percent of new COVID-19 cases in the week prior. The BA.2.12.1 strain had caused 19 percent of the new cases despite it only being detected in the US around mid-April.

"The Chinese mainland detecting the BA.2.3 variant for the first time may simply mean this virus was introduced to the country, not that the variant originated in China as some have assumed," the expert said.

The expert noted that BA.2.3's pathology is similar to the BA.2 variant that caused the latest outbreak in the Hong Kong Special Administrative Region. Therefore, people who are vaccinated and have received booster shots should be well protected against this variant, similar to how vaccines significantly lowered the risk of severe disease and mortality in Hong Kong.

According to Hong Kong public health authority data, the overall case fatality rate of its latest BA.2 Omicron outbreak was 0.74 percent, but soared to 2.97 percent for the unvaccinated.

For people who received one shot of a vaccine, the fatality rate was 0.97 percent, while it was 0.16 percent for those who had two doses and 0.04 percent for those with three doses.

Edsel Salvana, director of the Institute of Molecular Biology and Biotechnology at the University of the Philippines Manila, said in an article last month that it is very common for the COVID-19 virus to mutate given its high degree of transmission.

Given time, a virus will develop its own set of signature mutations to the point of being given its own sublineage, such as in the case of BA.2.3, he said. "There is no need to panic even as these new lineages evolve and spread as a result of continued transmission," he added. "Trusting vaccines and continuing to protect one another is the best way to remain resilient."