BA.2 is like Omicron's sister; Here's what we know about it so far
Queensland, Feb 3 (The Conversation): Cases of the SARS-CoV-2 variant Omicron have escalated globally over the past two months, with many countries experiencing peaks higher than previous variants.
Now we're seeing cases of a sub-variant of Omicron, known as BA.2, emerge in Australia and more than 50 countries.
Rather than a daughter of the Omicron variant BA.1 (or B.1.1.529), it's more helpful to think of BA.2 as Omicron's sister.
Remind me, what is a variant?
Viruses, and particularly RNA viruses such as SARS-CoV-2, make lots of mistakes when they reproduce. They can't correct these mistakes, so they have a relatively high rate of errors, or mutations, and are constantly evolving.
When the genetic code of a virus changes as a result of these mutations, it's referred to as a variant.
Omicron is a highly divergent variant, having accumulated more than 30 mutations in the spike protein. This has reduced the protection of antibodies from both prior infection and vaccination, and increased transmissibility.
When do health authorities worry about a new variant?
If changes in the genetic code are thought to have the potential to impact properties of the virus that make it more harmful, and there's significant transmission in multiple countries, it will be deemed a variant of interest .
If a variant of interest is then shown to be more infectious, evade protection from vaccination or previous infection, and/or impact the performance of tests or treatments, it is labelled a variant of concern .
The World Health Organisation (WHO) classified Omicron a variant of concern on November 26 because of its potential to cause higher reinfection rates, increased transmissibility and reduced vaccine protection.
What is the Omicron lineage?
A lineage, or sub-variant, is a genetically closely related group of virus variants derived from a common ancestor.
The Omicron variant comprises three sub-lineages: B.1.1.529 or BA.1, BA.2 and BA.3.
While the WHO has not given BA.2 a separate classification, the United Kingdom has labelled BA.2 a variant under investigation . So not yet a variant of interest or concern, based on WHO definitions, but one that is being watched closely.
This is not the first variant to have sub-lineages. Late last year, Delta plus or AY.4.2 was reported widely, then Omicron came along.
What's different about BA.2?
While the first sequences of BA.2 were submitted from the Philippines and we have now seen thousands of cases, including in the United States, the UK and some in Australia its origin is still unknown.
The exact properties of BA.2 are also still being investigated. While there is no evidence so far that it causes more severe disease, scientists do have some specific concerns.
1. It's harder to differentiate
A marker that helped differentiate Omicron (BA.1) from other SARS-CoV-2 variants on PCR tests is the absence of the the S gene, known as S gene target failure . But this is not the case for BA.2.
The inability to detect this lineage in this way has led some to label it the stealth sub-variant .
But it doesn't mean we can't diagnose BA.2 with PCR tests. It just means when someone tests positive for SARS-CoV-2, it will take us a little longer to know which variant is responsible, through genome sequencing. This was the case with previous variants.
2. It may be more infectious
Perhaps most concerning is emerging evidence BA.2 may be more infectious than the original Omicron, BA.1.
A preliminary study from Denmark, where BA.2 has largely replaced BA.1, suggests BA.2 increases unvaccinated people's susceptibility of infection by just over two times when compared to BA.1.
The researchers suggest fully vaccinated people are 2.5 times more susceptible to BA.2 than BA.1, and those who were booster vaccinated are nearly three times more susceptible.
The study examined more than 2,000 primary household cases of BA.2 to determine the number of cases that arose during a seven-day follow up period.
The researchers also estimated the secondary attack rate (basically, the probability infection occurs) to be 29% for households infected with BA.1 versus 39% for those infected with BA.2.
This Danish study is still a preprint, meaning it's yet to be checked by independent scientists, so more research is needed to confirm if BA.2 is truly more infectious than BA.1.
We're likely to see new variants We should expect new variants, sub-variants and lineages to continue to emerge. With such high levels of transmission, the virus has abundant opportunity to reproduce and for errors or mutations to continue to arise.
The way to address this, of course, is to try to slow transmission and reduce the susceptible pool of hosts in which the virus can freely replicate.
Strategies such as social distancing and mask-wearing, as well as increasing vaccination rates globally, will slow the emergence of new variants and lineages. (The Conversation)
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Deepika Kumari leads Indian recurve archery team to dramatic World Cup gold
Shanghai (PTI): The Indian trio of Deepika Kumari, Ankita Bhakat and teenager Kumkum Mohod held their nerve in a tense shoot-off to beat home favourites China and clinch the women's recurve team gold medal at the Archery World Cup Stage 2 here on Sunday.
In a final marked by fluctuating fortunes, India edged past the home side 5-4 (28-26) in the shoot-off after the four-set regulation ended 4-4.
The victory was especially sweeter as India had earlier stunned record 10-time Olympic champions South Korea in the semifinals en route to their first World Cup women's team gold since 2021.
Deepika, who was also part of India's World Cup-winning teams in Guatemala City and Paris in 2021, now has seven World Cup team gold medals to her name since 2010.
It was also the Indian women recurve team's first World Cup medal in three years, its previous podium finish coming in Stage 4 in Paris in 2023 where Ankita was a member of the winning team.
India's campaign in Shanghai has thus already yielded two medals after compound archer Sahil Jadhav opened the country's account, securing a bronze on Saturday.
India also remained in contention for another podium finish later in the day with recurve archer Simranjeet Kaur set to compete in the semifinals. She is a win away from her maiden individual World Cup medal.
Travelling without a full-time national coach amid the continuing impasse over appointments, it was the vastly experienced Deepika who led from the front, constantly motivating her teammates during breaks and changeovers.
Prafull Dange, who was the designated women's recurve coach after his ward Kumkum topped the national trials, largely remained in the background as Deepika guided the side through the pressure moments against a hostile home crowd and vocal Chinese support staff.
Against a young Chinese side comprising Zhu Jingyi, Huang Yuwei and teenage archer Yu Qi, who all made their World Cup debuts only last year, India looked in control initially but nearly let the match slip after taking the opening set (54-53).
Shooting last in the Indian order, Deepika set the tone with successive 10s as India edged the first set despite Ankita (8-8) and 17-year-old Kumkum (10-8) putting up an inconsistent show.
Deepika continued her fine rhythm in the second set with another perfect 10 as India briefly held a one-point advantage (28-27) midway through the end. But China responded strongly with two 9s and a 10 in their final three arrows of the second set to post 55.
Ankita replied with a 9, but Kumkum managed only an 8, leaving Deepika needing a 10 to level the set.
The four-time Olympian, however, slipped to a 7 as India lost the set 52-55 and China drew level at 2-2.
The hosts then moved ahead in the third set. The teams were initially tied at 56, but a review upgraded China's final arrow from 8 to 9, handing them the set 57-56 and a 4-2 lead.
India appeared on the verge of defeat in the fourth set despite Deepika rediscovering her touch with two 10s. Kumkum's final arrow landed in the 7-ring as India posted a modest 54.
China required two 10s and a 9 from their last three arrows to seal the match.
Zhu and Huang delivered perfect 10s, leaving 18-year-old Yu Qi needing a 9 for victory in front of the home crowd.
But the youngster shot an 8, allowing India a dramatic escape and forcing a shoot-off.
The Indians peaked at the right moment in the decider. Ankita opened with a 9, Kumkum followed with a superb 10, and Deepika calmly delivered a 9 when only an 8 was needed to seal the title.
