Explainer: India and Omicron BF.7 Covid risk

December 26, 2022:

The BF.7-led Covid-19 surge in China has fanned concerns in India about this viral sub-variant. However, DrGagandeep Kang, who was involved in India’s Covid-19 decision-making in the early months of the pandemic, has said India has little reason for worry. Sarthak Ray takes a look at what the data and experts are saying

Why is the Covid situation so serious in China?

When China ended its zero Covid policy (in place since the pandemic started), a large chunk of its population didn’t have any natural exposure to SARS CoV-2, the Covid virus, thanks to the draconian zero Covid restrictions. Moreover, many in its elderly population haven’t been vaccinated against Covid, and booster penetration in the vaccinated pool is low as well. Also, the expert consensus is that the nationally  developed vaccines China used have much lower efficacy than vaccines rolled out elsewhere, including India.

The BF.7 sub-variant, which is the dominant strain in China, is highly infectious. Besides, the surge coinciding with the season when respiratory diseases are common has led to a flood in hospitalisation cases.

What is the BF.7 sub-variant of SARS CoV-2?

BF.7 (aka BA.5.2.1.7) is a sub-lineage of the Omicron BA.5 variant. The R346T mutation—which confers superior receptor-binding powers, allowing the virus to infect a human cell much more easily—is present in the BA.5 parental line and its sub-lineages, including BF.7. But BF.7 has an additional mutation, giving it even higher infectivity. Indeed, data from China shows that a BF.7 infected person can transmit to 10-19 others versus about 5 for BA.1 (the original Omicron variant).

A study published in Cell Host & Microbe in November found that, compared to the original virus (Alpha), BF.7 exhibited 4.4X higher neutralisation resistance to antibodies isolated from US patients who had been infected by recent Omicron variants. Resistance to antibodies from vaccinated US healthcare workers was a whopping 11X higher than Alpha’s.

The India picture

BF.7 was first detected in India in September this year, by the Gujarat Biotechnology Research Centre. None of the deaths mapped to any of the circulating variants have been attributed to BF.7. Four BF.7 cases have been reported in India since July this year.

Experts, including Insacog scientists, have said there is no reason for concern. The Centre, though, has advised pre-emptive caution.

Symptoms of BF.7

BF.7 primarily manifests upper respiratory tract ailments, with congestion in the throat and upper parts of the lungs. Other symptoms include fever, sore throat, runny nose, and cough. Some patients have also reported vomiting and diarrhoea.

The symptoms are not very different from those seen in other Omicron variants. But immunocompromised individuals and those with comorbidities may exhibit more serious symptoms. Experts advise testing at the onset of symptoms.

Why India may not have much reason for worry…

Data from China suggest BF.7 has a higher transmission rate than other variants, a shorter incubation period, and a greater capacity to infect persons who have had previous infections or have received vaccine doses.

BF.7 cases are also rising in the West, including the US, Belgium, the UK, France, Germany, and Denmark. While worldwide cumulative prevalence (February 2021 – December 15, 2022) is less than 0.5%, the prevalence in Belgium is 11% and in Denmark is 7%. However, the UK, which had two months ago sounded concern, has dialled down its estimation of BF.7’s seriousness.

Experts believe that India doesn’t face a grave threat from the variant, given its near-total vaccine cover at the population level—220 crore doses, including boosters, administered—as well as the levels of natural exposure. The Delta variant, some experts have said, helped the population develop a certain degree of immunity to the virus that was topped up by the Omicron wave.

However, the Centre has rightly urged caution. Even if it doesn’t cause severe morbidity and mortality in a large chunk of the population, absolute infection numbers from its high infectivity could drive up hospitalisation cases and deaths.

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* N460K mutation most critical for BF.7 neutralisation resistance

* <0.5% global prevalence as per outbreak info

* 11%  in Belgium

* 7%  in Denmark

* 4.47 croreCovid cases in India so far

Financialexpress.com