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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Texas halts H-1B visas at state universities, agencies; to affect Indians
Houston (US) (PTI): Texas Governor Greg Abbott has ordered state agencies and public universities to immediately halt new H-1B visa petitions, tightening hiring rules at taxpayer-funded institutions, a step likely to impact Indian professionals.
The freeze will remain in effect through May 2027.
The directive issued on Tuesday said that the state agencies and public universities must stop filing new petitions unless they receive written approval from the Texas Workforce Commission.
The governor's order, in a red state that is home to thousands of H-1B visa holders, comes as the Trump administration has initiated steps to reshape the visa programme.
“In light of recent reports of abuse in the federal H-1B visa programme, and amid the federal government’s ongoing review of that programme to ensure American jobs are going to American workers, I am directing all state agencies to immediately freeze new H-1B visa petitions as outlined in this letter,” Abbot said.
Institutions must also report on H-1B usage, including numbers, job roles, countries of origin, and visa expiry dates, the letter said.
US President Donald Trump on September 19 last year signed a proclamation ‘Restriction on entry of certain non-immigrant workers’ that restricted the entry into the US of those workers whose H-1B petitions are not accompanied or supplemented by a payment of USD 1,00,000.
The H1-B visa fee of USD 1,00,000 would be applicable only to new applicants, i.e. all new H-1B visa petitions submitted after September 21, including those for the FY2026 lottery.
Indians make up an estimated 71 per cent of all approved H-1B applications in recent years, according to US Citizenship and Immigration Services (USCIS), with China in the second spot. The major fields include technology, engineering, medicine, and research.
Tata Consultancy Services (TCS) is the second-highest beneficiary with 5,505 approved H-1B visas in 2025, after Amazon (10,044 workers on H-1B visas), according to the USCIS. Other top beneficiaries include Microsoft (5,189), Meta (5,123), Apple (4,202), Google (4,181), Deloitte (2,353), Infosys (2,004), Wipro (1,523) and Tech Mahindra Americas (951).
Texas public universities employ hundreds of foreign faculty and researchers, many from India, across engineering, healthcare, and technology fields.
Date from Open Doors -- a comprehensive information resource on international students and scholars studying or teaching at higher education institutions in the US -- for 2022-2023 showed 2,70,000 students from India embarked on graduate and undergraduate degrees in US universities, accounting for 25 per cent of the international student population in the US and 1.5 per cent of the total student population.
Indian students infuse roughly USD 10 billion annually into universities and related businesses across the country through tuition and other expenses – while also creating around 93,000 jobs, according to the Open Doors data.
Analysts warn the freeze could slow recruitment of highly skilled professionals, affecting academic research and innovation.
Supporters say the directive protects local jobs, while critics caution it could weaken Texas’ competitiveness in higher education and research.
The order comes amid broader debate in the US over skilled immigration and state-level interventions in federal programmes.
H-1B visas allow US companies to hire technically-skilled professionals that are not easily available in America. Initially granted for three years, these can be extended for another three years.
In September 2025, Trump had also signed an executive order ‘The Gold Card’, aimed at setting up a new visa pathway for those committed to supporting the United States; with individuals who can pay USD 1 million to the US Treasury, or USD 2 million if a corporation is sponsoring them, to get access to expedited visa treatment and a path to a Green Card.
