Explained: What's BF.7 Omicron Sub-Variant That's Driving China's Covid Wave, What Is Its Severity?

Projections say 1.3-2.1 million people could die in China from the Covid-19 surge. The Chinese Covid-19 surge is being driven BF.7 Omicron sub-variant, which has proved to be highly infectious in China.

China Covid-19 Outbreak

A new sub-variant of the highly infectious Omicron variant of coronavirus is driving the current surge of Covid-19 infections in China. 

China is currently witnessing an unprecedented Covid-19 surge and Chinese healthcare system is beind overwhelmed. Shortages of medicines have also been reported amid suggestions that Chinese authorities are covering up the true extend of outbreaks.

The China's Covid-19 surge is being driven by BF.7 Omicron sub-variant. The surge follows the relaxation of China's 'Zero Covid' policy after a wave of intense nationwide protests. Projections show that China's Covid-19 situation is expected to get worse through the winters. 

Here we explain what's new sub-variant BF.7, how it's driving China's surge, and what projections say about China's Covid situation's future.

What's BF.7 Omicron sub-variant?

The BF.7 Omicron sub-variant's full name is BA. 

SARS-CoV-2, the virus that causes Covid-19 disease, has evolved since it first emerged in 2019 just like any other virus.

As SARS-CoV-2 evolved, it acquired a number of mutations which led to a number of variants, such as Alpha, Delta, and Omicron. These variants further went through mutations to form branches of themselves, leading to sub-variants. 

Every variant has a number of sub-variants. The deadly Delta variant behind India's second wave has up to 200 sub-variants. 

What we know of BF.7 Omicron sub-variant in China?

It's known that the BF.7 Omicron sub-variant is driving the current Covid-19 surge in China.

"A new and highly transmissible BF.7 strain of the Omicron variant has been found to be behind a wider surge of COVID infections in China," said the Indian Ministry of Health on Wednesday. 

Though the virus is primarily driving the surge in China, it has been found in the United States, Denmark, Germany, France, and India. 

Chinese experts have said that it is much more transmissible than earlier coronavirus strains. It's reportedly the main strain in Beijing which is reporting a surge of infections.

The BF.7 Omicron sub-variants has the "strongest infection ability" so far poses risk of "hidden spread", according to Beijing-based expert Li Tongzeng.

"Compared with the BA.1, BA.2 and BA.5 variants detected previously, Omicron BF.7 has more immune escape capability, a shorter incubation period and faster transmission rate," The Chinese state-run Global Times quoted Tongzeng as saying, who is medical expert at Beijing's Xiaotangshan Hospital.

Tongaeng said the reproduction number (R0) of the BF.7 Omicron sub-variant is 10 whereas it was 5-6 for Delta variant.

R0 is a number that measures how transmissible an infectious disease is. The higher the number, the more infectious it is.

"R0 tells you the average number of people who will contract a contagious disease from one person with that disease...For example, if a disease has an R0 of 18, a person who has the disease will transmit it to an average of 18 other people," says Healthline

The Global Times reported that the 10 R0 of BF.7 is the lower limit. It can cross 18 in some cases.

Though BF.7 has very high transmissibility, its symptoms are similar to earlier Omicron sub-variants, as per Global Times. These are:

  • Fever
  • Cough
  • Sore throat
  • Vomiting
  • Diarrhea, etc

What makes BF.7 different and concerning?

As the virus mutates over time, some of the mutations that the resultant variants and sub-variants acquire enable them to work better. For example, the Delta variant is deadlier and Omicron variant is highly transmissible because of their unique mutations.

There are some noticable mutations in BF.7 sub-variant, according to Fortune.

"The new subvariant has a change in the spike protein —a feature that allows it to enter cells— seen in other Omicron strains making headway. It also has a change in the nucleotide sequence —sometimes referred to as the blueprint of an organism— that could cause it to behave differently than other subvariants," reported Fortune.

These mutations give BF.7 some immune-evasive abilities, which means it can escape immunity from vaccine or previous infection, according to microbiology expert Manal Mohammed of University of Westminster.

"A recent study examined the neutralisation of BF.7 in sera (a component of blood that should contain antibodies) from triple-vaccinated healthcare workers, as well as patients infected during the omicron BA.1 and BA.5 waves of the pandemic. BF.7 was resistant to neutralisation, driven partly by the R346T mutation," notes Mohammed in an article for The Conversation.

She adds that though BF.7 causes concerns, it's not having an effect similar to China in the United States or United Kingdom. Citing recent data, she notes that BF.7 amounts to just 5.7 per cent cases in USA and 7 per cent in UK.

Mohammed says the BF.7 severe impact in China could be because of lower vaccination or lower immunity among people, either from lower vaccination rates or fewer previous infections.

"BF.7’s high R0 might be due in part to a low level of immunity in the Chinese population from previous infection, and possibly vaccination too. We should, of course, be cautious about the data from China as it’s based on reports, not peer-reviewed evidence yet," notes Mohammed.


China has rejected foreign vaccines and has relied on Chinese vaccines known to be less effective. This has been flagged as possible reason for the current surge in infections.

"The lower efficacy of the two key Chinese-made vaccines became a concern early in the pandemic, when global health experts suggested adding a third shot to protect older people. Vaccines from two companies, Sinovac and Sinopharm, are based on an inactivated form of the virus. The mRNA vaccines, by contrast, instruct the body’s own cells to build a replica of a key coronavirus protein to trigger an immune response," reports The Washington Post.


Up to 2 million can die in China: Projections

Projections of infections and deaths in China say that 1.3-2.1 million people could die in China in near future from Covid-19.

PTI reported projections by The Economist and The Lancet.

The Economist reports around 1.5 million Chinese could die based on its model that calculates the trajectory of China's outbreak under different scenarios based on estimates of the rates at which people become infected, get sick, recover or die – referred to as the SEIR model, according to PTI.

It reports The Lancet’s report quoting a projection saying that somewhere between 1.3 and 2.1 million people could die from Covid-19 after China re-opens.


There are also signs that Chinese authorities are covering up the true extent of the Covid-19 outbreak.

Reuters reported that dozens of funeral took place in Beijing with funeral staff in hazmat suits despite China reporting zero Covid-19 deaths.

"At a crematorium in Beijing's Tongzhou district, a Reuters witness saw a queue of about 40 hearses waiting to enter while the parking lot was full. Inside, family and friends, many wearing traditional white clothing and headbands of mourning, gathered around about 20 coffins awaiting cremation. Staff wore hazmat suits and smoke rose from five of the 15 furnaces," reported Reuters.


It also reported that medicines are in shortage at places in China.

"The abrupt change of policy has caught a fragile health system unprepared and hospitals are scrambling for beds and blood, pharmacies for drugs, and authorities are racing to build special clinics," reports Reuters about how Chinese healthcare system is being overwhelmed.