Shenzhen has discovered a new Omicron subvariant BF.7 among the city’s COVID-19 infections detected since Sunday, the city’s health commission said yesterday. It was the first time that a new Omicron subvariant had appeared in Shenzhen.

The new strain is the abbreviated form of subvariant BA.5.2.1.7 and is a sublineage of subvariant BA.5. Compared with subvariants BA.4 or BA.5, BF.7 is more contagious and spreads faster, which makes it easier to cause large-scale virus spread, according to the commission.

A new round of COVID-19 outbreak has occurred in Shenzhen since the end of the National Day holiday. Most of the cases involved returning or inbound travelers to the city and the local infections associated with them. 

The Shenzhen Center for Disease Control and Prevention (CDC) has carried out comparative analysis of virus genome sequencing on all cases reported in the city since Sunday, and the sequencing results showed that subvariants BF.7, BA.2.76 and BA.2.2 were responsible for most of the infections.

The city has adjusted its prevention and control measures, requiring all personnel coming or returning to Shenzhen to present negative 48-hour nucleic acid test results and undergo nucleic acid tests daily for three consecutive days. 

Starting yesterday, people leaving Shenzhen must have negative 48-hour COVID test results, the city’s health authority said yesterday.

Returning and inbound travelers from high-risk areas outside the city must be put under a seven-day centralized quarantine and take five COVID tests within the period, while those from medium-risk areas will be placed under home quarantine for seven days and take three COVID tests in the period.

Those from cities with high- and medium-risk areas are not allowed to participate in gatherings and going to crowded places within seven days and receiving visiting guests within the first three days.

The risk of a large-scale outbreak in Shenzhen is low and the COVID prevention and control situation is generally controllable as all COVID cases reported in the city were detected early, according to the commission.

Experts from the Shenzhen CDC have warned that wearing masks scientifically can effectively reduce cross infection, lower transmission risk and contain virus spread. It is also the simplest, most convenient and most economical prevention and control measure.

The reiteration of the importance of wearing masks properly came after the city’s epidemiological investigations found that many COVID infections reported recently were caused by not wearing masks or incorrect mask wearing.

A man was confirmed infected with the subvariant BF.7 after returning to Shenzhen from a trip from Inner Mongolia on Sunday. According to a preliminary epidemiological investigation, a pedestrian was also found infected after they bumped into each other on the roadside Saturday. Both were not wearing masks at that moment and the man was linked to more than 20 subsequent infections.

Meanwhile, two locals — one man and one woman — are being investigated by Futian police on suspicion of hindering the prevention and control of infectious diseases. According to the CDC’s epidemiological investigation, before their COVID test results came out positive Sunday after returning from outbound trips, they did not wear masks in public places and participated in gatherings, resulting in virus spread.

The city reported 33 locally transmitted confirmed COVID cases Monday, among which, 27 were associated with returning or inbound travelers to Shenzhen from other cities and provinces.