COVID-19 omicron emerged in late 2021 and has rapidly evolved into several subvariants since then. Recently, BF.7 was found to be the predominant subvariant in Beijing, and it is thought to be a factor in the nationwide increase of COVID-19 infections in China.
But what exactly is this new variant, and should we be worried about it? Worrying reports about this variant’s traits have come out of China, but outside of that country, it doesn’t appear to be expanding at an alarming rate. Take a look at our current understanding.[After this article was published, there were spikes in countries like the US, Japan, and South Korea.]
As an offshoot of the BA.5 omicron variant, BF.7 (or BA.22.214.171.124) is the abbreviation to remember.
Among the omicron subvariants in China, BF.7 reportedly has the highest infection rate due to its rapid transmission, short incubation period, and increased ability to infect individuals who have either been previously infected with COVID-19 or who have received a vaccination against the virus.
As a point of reference, it is estimated that BF.7 has an R0 (basic reproduction number) between 10 and 18.6. As a result, an infected person can potentially infect anywhere from 10.2 to 18.6 others. In studies, omicron has been found to have an average R0 of 5.08.
It is believed that the difficulty in controlling the epidemic in China is due to the high transmission rate of BF.7 and the risk of hidden spread due to a large number of asymptomatic carriers.
When It Comes To BF.7, How Much Do We Really Know?
Virus mutations give rise to new lineages and sub-lineages, much like the branches and trunk of the SARS-CoV-2 tree. BF.7 is synonymous with BA.126.96.36.199, a branch of the BA.5 sub-family of the Omicron sub-family.
The BF.7 sub-variant has 4.4-fold higher neutralization resistance than the original D614G variant, according to a study published in the journal Cell Host and Microbe earlier this month. This means that antibodies from vaccinated or infected individuals were less likely to destroy BF.7 than the original Wuhan virus that spread globally in 2020.
Yet another Omicron sub-variant, BQ.1, was reported in the same study to have neutralization resistance more than ten times as high as BF.7.
In populations, the likelihood of a variant spreading and displacing other variants increases if it has a higher neutralization resistance.
Over 5% of US cases and 7.26% of UK cases in October were attributable to BF.7. Western researchers were keeping a close eye on this variant, but so far, they haven’t noticed any spikes in cases or hospitalizations.
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Does BF.7 Have A Footprint In India As Well?
Omicron BA.1 and BA.2 were the primary strains responsible for the January 2022 outbreak in India. Consequently, there were hardly any cases of BF.7 in India because the subsequent sub-variants, BA.4 and BA.5, were never as common there as they were in Europe (which is an offshoot of BA.5).
According to information gathered by India’s national SARS-CoV-2 genome sequencing network in the month of November, only 2.5% of cases were associated with the BA.5 lineage. To date, recombinant variant XBB has been the most prevalent in India, making up 65.6% of all cases during the month of November.
So, Why Did Things Turn Out Differently In China?
“China is now experiencing the typical Omicron surge that other countries have already witnessed, and just like the one Hong Kong saw when it relaxed its restrictions,” said Dr. Anurag Agarwal, the former head of India’s Covid-19 genome sequencing consortium INSACOG.
Since the population had been vaccinated and exposed to the virus before, we assumed that the Omicron wave would be less severe. On top of that, we have already “paid the price,” if you will, during the Delta wave (of April-May 2021). Even though many passed away, those who made it through were more resilient. “We (India) do have a younger population,” Dr. Agarwal said, “and Omicron has mainly been killing its elderly victims.”
Even highly contagious variants haven’t caused a pandemic because most people get over the initial fever, cough, and sore throat and feel fine after a few days.
According to Dr. Agarwal, the only countries that paid a negligible amount of this “price” were the ones that remained closed until they were able to vaccinate everyone and then reopened: Australia, New Zealand, and Singapore.
He went on to say that the rise in infections was not accompanied by a rise in the number of severe cases that required hospitalization or led to deaths, so case numbers were becoming less relevant.
BF.7 Around The World
India, the United States, the United Kingdom, and a number of European countries including Belgium, Germany, France, and Denmark have all reported finding traces of BF.7.
Despite the fact that BF.7 has immune-evading properties and there are concerning signs of its spread in China, the variant appears to be holding steady in most other countries. As an illustration, as of December 10th, it was thought that 5.7% of infections had been caused by it in the United States, down from 6.6% the week before.
Although BF.7 was listed in an October technical briefing by the UK Health Security Agency as one of the most worrisome variants in terms of growth and neutralization data (it accounted for over 7% of cases at the time), the most recent briefing claims that BF.7 has been de-escalated due to reduced incidence and low growth rates in the UK.
For some reason, the situation appears to be different in China, but we can’t pinpoint why. The low level of immunity in the Chinese population from the previous infection and possibly vaccination could contribute to BF.7’s high R0. Since the Chinese data is based on reports rather than peer-reviewed evidence, caution is warranted when using it.
Compared to SARS-CoV-2 and its Delta variant, the Omicron variant spreads more easily, as reported by the CDC. An alarming increase in COVID-19 cases was seen in South Africa soon after the variant emerged, with the number of cases rising from 300 per day in the middle of November 2021 to 3,000 per day by the end of the month.