Since the COVID variant omicron emerged in late 2021, it has rapidly evolved into multiple sub-variants. One of these sub-variants, BF.7, was recently identified as the main variant spreading in Beijing and is contributing to a wider increase in COVID infections in China.
While reports from China about the features of this variant are alarming, it doesn’t seem to pose much of a threat elsewhere in the world.
BF.7, short for BA.5.2.1.7, is a sub-lineage of the BA.5 omicron variant
Reports from China indicate that BF.7 has the strongest infectivity among the omicron sub-variants in the country, transmits more rapidly than other variants, has a shorter incubation period, and includes people with previous COVID infection or vaccination, or both. indicates higher infectivity.
BF.7 is believed to have an R0 of 10 to 18.6, i.e. a basic reproduction number. This means that an infected person will transmit the virus to an average of 10 to 18.6 people. Studies show that the average R0 of the micron is 5.08. It seems that the high transmission rate of BF.7, which is taken with the risk of hidden spread due to many asymptomatic carriers, causes significant difficulties in the control of the epidemic in China.
The symptoms of an infection with BF.7 are similar to those associated with other omicron sub-variants, primarily upper respiratory tract symptoms. Patients may have fever, cough, sore throat, runny nose, and malaise, among other symptoms. A small number of people may also experience gastrointestinal symptoms such as vomiting and diarrhea.
BF.7 can cause more serious illness in people with compromised immune systems. As Omicron has evolved, we have seen the emergence of new subvariants that are better able to evade immunization from vaccination or previous infection, and BF.7 is no different.
BF.7 has a specific mutation, R346T, in the spike protein of SARS-CoV-2 (a protein on the surface of the virus that allows it to attach to and infect our cells). This mutation, which we also see in the “parent” variant of BF.7, BA.5, is associated with an increased capacity of the virus to evade neutralizing antibodies produced by vaccines or previous infection.
A recent study examined the neutralization of BF.7 in the serum (blood component that must contain antibodies) of triple-vaccinated healthcare workers, as well as patients infected during the micron BA.1 and BA.5 waves of the epidemic. BF.7 was resistant to neutralization driven in part by the R346T mutation.
BF.7 has also been detected in many other countries around the world, including India, the USA, the UK and many European countries such as Belgium, Germany, France and Denmark.
7, and despite alarming signs of its growth in China, the variant appears to have a steady presence elsewhere. For example, it is estimated to be responsible for 5.7% of infections in the US up to December 10, up from 6.6% the previous week.
While the UK Health Safety Agency identified BF.7 as one of the most relevant variables for both growth and neutralization data in a technical briefing published in October (it accounted for over 7% of cases at the time), the most recent briefing was BF.7 He says the ‘ is reduced in the UK due to declining incidence and low growth rates.
Why is the situation different in China?
It is not known exactly why the situation in China looks different. The high R0 of BF.7 may be due in part to the low level of immunity in the Chinese population resulting from previous infection and possibly vaccination. We need to pay attention to data from China, as it is based on reports, not yet peer-reviewed evidence.
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