China has reported the first case of Omicron subvariant BA.2.12.1, a mutation that has shown transmissibility that is about 23-27 percent higher than that of BA.2, in South China's Guangdong Province, according to a weekly report issued by the Chinese Center for Disease Control and Prevention (China CDC).
The patient, a 27-year-old Chinese male, arrived on international flight KQ880 from Nairobi, Kenya in Guangzhou on April 23. All passengers were transferred to a quarantine hotel for the routine 14-day medical observation after landing.
The patient, having received full vaccination and denying exposure to other infected cases in the previous 14 days, tested positive for COVID-19 on April 27. After diagnosis, he was transferred to Guangzhou Eighth People's Hospital for treatment.
On April 30, the virus sequence from the patient's nasal swab sample showed that he was infected with the Omicron subvariant BA.2.12.1. The sequence has been submitted to the National Genomics Data Center for further studies.
The World Health Organization (WHO) reminded countries to closely monitor the subvariant on May 4. Compared with other Omicron variants, BA.2.12.1 shows stronger resistance to immune reaction, even after individuals have had a booster dose.
The fast spread of the subvariant has led to the resurgence of the epidemic in many parts of the US, and cases have been reported in at least 23 countries and regions, WHO's technical lead on COVID Maria Van Kerkhov said during a Live Q&A on May 11.
In some parts of the US, BA.2.12.1 has already become the dominant subvariant. In the states of New York and New Jersey, the strain is responsible for 66 percent of cases, US media reported last week.