London Daily

Focus on the big picture.
Monday, Oct 20, 2025

Omicron BA.2: What we know about the Covid sub-variant

Omicron BA.2: What we know about the Covid sub-variant

The highly transmissible Omicron variant now accounts for half of the world's infections.

But Omicron is an umbrella term for several closely related lineages of the SARS-CoV-2 coronavirus, the most common of which is the BA.1 lineage.

Now more countries, particularly in Asia and Europe, are reporting an increase in cases driven by BA.2.

While BA.2 appears to be more transmissible than previous variants, there is no data yet to suggest that it is any more severe.

So how worried should we be about this emerging variant? Here is what we know about it.

What is BA.2?


As viruses mutate into new variants, they sometimes split or branch off into sub-lineages. The Delta variant, for example, comprises 200 different sub-variants.

The same happened with Omicron, which includes the lineages BA.1, BA.2, BA.3 and B.1.1.529.

BA.1 accounts for most of the cases. According to the World Health Organization (WHO), nearly 99% of viral DNA submitted to the global GISAID database as of 25 January were identified as this sub-variant.

BA.2 was first detected in the Philippines


While BA.1 and BA.2 are similar, they are 20 mutations apart.

It is not clear where BA.2 originated, but it was first detected in the Philippines in November.

Where is BA.2 spreading?


The sub-variant of Omicron has been detected in 57 countries now, the WHO says. In some countries, BA.2 accounts for more than half of sequenced Omicron cases, it adds.

In some places, growth in recorded cases of the sub-variant has been sharp.

According to Denmark's Statens Serum Institut (SSI), BA.2 infections rose to account for about half of the country's reported Covid cases in January.

India is another country where BA.2 is rapidly replacing the Delta and Omicron BA.1 variant, according to molecular biologist Bijaya Dhakal.

It is already the dominant variant in several states and likely drove the country's recent third wave of infections.


The Philippines' Department of Health (DOH) said the BA.2 sub-lineage was already prevalent in samples it received at the end of January.

And in England, more than 1,000 confirmed cases of BA.2 have been identified, according to the UK Health Security Agency (UKHSA). It has been designated a "variant under investigation" by British health authorities, meaning they are keeping a close watch on it, but are not overly concerned by it.

BA.2 infections in Germany are also growing faster than BA.1 and Delta, according to Dr Meera Chand, Covid-19 director at the UKHSA.

Is BA.2 more transmissible?


A study of 8,500 households and 18,000 individuals conducted by Denmark's SSI found that BA.2 was "substantially" more transmissible than BA.1.

The study also showed evidence to suggest that the BA.2 sub-variant is better able to evade vaccines.

About half on new cases in Denmark are caused by BA.2


However, vaccinated people are still less likely to get infected than unvaccinated individuals, and they are also less likely to pass it on.

A separate UK study also found higher transmissibility for BA.2 compared to BA.1.

But the preliminary assessment found no evidence that vaccines would be any less effective against symptomatic disease for either sub-variant.

Is BA.2 more dangerous?


There is no data to suggest that BA.2 leads to more severe disease than previous Omicron sub-variants.

"Looking at other countries where BA.2 is now overtaking, we're not seeing any higher bumps in hospitalisation than expected," the WHO's Dr Boris Pavlin says.

Francois Balloux, Professor of Computational Systems Biology and director of the UCL Genetics Institute, said that BA.1 and BA.2 "can be considered as two epidemiologically largely equivalent sub-lineages of Omicron".

As with previous variants, experts believe vaccines will continue to be highly effective against severe illness, hospitalisation, and death.

Dr Chand said: "So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1.

"We must remain vigilant and take up vaccinations. We should all continue to test regularly with LFDs [lateral flow devices] and take a PCR [polymerase chain reaction] test if symptoms develop."


No cause for alarm at this stage


Scientists in the UK and abroad are closely monitoring BA.2, a sub-variant of Omicron.

At the moment there is much that is not yet clear.

It appears to have a growth advantage compared to the version of Omicron, BA.1, that has swept the globe. Analysis by the UKHSA suggests it could be substantial, although there is a risk of over-estimating growth advantage in the early stages.

What we know is that it is certainly growing as a proportion of overall cases in the UK.

Because of a quirk in how it shows up in test results, we can see the numbers of suspected BA.2 doubled in the week up to 24 January.

But at that point the sub-variant still appeared to account for less than one in 20 cases.

That contrasts to Denmark, where it has become dominant.

A preliminary assessment by UKHSA did not find a difference in vaccine effectiveness, although it said there was no data yet available on severity.

But it is worth noting that Denmark has seen similar trends in terms of hospital admissions and intensive care as the UK has, suggesting BA.2 does not mark a sea-change in severity.

And even if it does become the dominant version of Omicron, it may not actually alter the trajectory of the pandemic in countries that have seen a big wave of BA.1. That's because there could be cross-immunity - an infection with BA.1 could offer some protection against BA.2.

It is one for the scientists to watch, rather than for the public to be alarmed about at this stage.

Newsletter

Related Articles

0:00
0:00
Close
This Is How the 'Heist of the Century' Was Carried Out at the Louvre in Seven Minutes: France Humiliated as Crown with 2,000 Diamonds Vanishes
China Warns UK of ‘Consequences’ After Delay to London Embassy Approval
France’s Wealthy Shift Billions to Luxembourg and Switzerland Amid Tax and Political Turmoil
"Sniper Position": Observation Post Targeting 'Air Force One' Found Before Trump’s Arrival in Florida
Shouting Match at the White House: 'Trump Cursed, Threw Maps, and Told Zelensky – "Putin Will Destroy You"'
Windows’ Own ‘Siri’ Has Arrived: You Can Now Talk to Your Computer
Thailand and Singapore Investigate Cambodian-Based Prince Group as U.S. and U.K. Sanctions Unfold
‘No Kings’ Protests Inflate Numbers — But History Shows Nations Collapse Without Strong Executive Power
Chinese Tech Giants Halt Stablecoin Launches After Beijing’s Regulatory Intervention
Manhattan Jury Holds BNP Paribas Liable for Enabling Sudanese Government Abuses
Trump Orders Immediate Release of Former Congressman George Santos After Commuting Prison Sentence
S&P Downgrades France’s Credit Rating, Citing Soaring Debt and Political Instability
Ofcom Rules BBC’s Gaza Documentary ‘Materially Misleading’ Over Narrator’s Hamas Ties
Diane Keaton’s Cause of Death Revealed as Pneumonia, Family Confirms
Former Lostprophets Frontman Ian Watkins Stabbed to Death in British Prison
"The Tsunami Is Coming, and It’s Massive": The World’s Richest Man Unveils a New AI Vision
Outsider, Heroine, Trailblazer: Diane Keaton Was Always a Little Strange — and Forever One of a Kind
Dramatic Development in the Death of 'Mango' Founder: Billionaire's Son Suspected of Murder
Two Years of Darkness: The Harrowing Testimonies of Israeli Hostages Emerging From Gaza Captivity
EU Moves to Use Frozen Russian Assets to Buy U.S. Weapons for Ukraine
Europe Emerges as the Biggest Casualty in U.S.-China Rare Earth Rivalry
HSBC Confronts Strategic Crossroads as NAB Seeks Only Retail Arm in Australia Exit
U.S. Chamber Sues Trump Over $100,000 H-1B Visa Fee
Shenzhen Expo Spotlights China’s Quantum Step in Semiconductor Self-Reliance
China Accelerates to the Forefront in Global Nuclear Fusion Race
Yachts, Private Jets, and a Picasso Painting: Exposed as 'One of the Largest Frauds in History'
Australia’s Wedgetail Spies Aid NATO Response as Russian MiGs Breach Estonian Airspace
McGowan Urges Chalmers to Cut Spending Over Tax Hike to Close $20 Billion Budget Gap
Victoria Orders Review of Transgender Prison Placement Amid Safety Concerns for Female Inmates
U.S. Treasury Mobilises New $20 Billion Debt Facility to Stabilise Argentina
French Business Leaders Decry Budget as Macron’s Pro-Enterprise Promise Undermined
Trump Claims Modi Pledged India Would End Russian Oil Imports Amid U.S. Tariff Pressure
Surging AI Startup Valuations Fuel Bubble Concerns Among Top Investors
Australian Punter Archie Wilson Tears Up During Nebraska Press Conference, Sparking Conversation on Male Vulnerability
Australia Confirms U.S. Access to Upgraded Submarine Shipyard Under AUKUS Deal
“Firepower” Promised for Ukraine as NATO Ministers Meet — But U.S. Tomahawks Remain Undecided
Brands Confront New Dilemma as Extremists Adopt Fashion Labels
The Sydney Sweeney and Jeans Storm: “The Outcome Surpassed Our Wildest Dreams”
Erika Kirk Delivers Moving Tribute at White House as Trump Awards Charlie Presidential Medal of Freedom
British Food Influencer ‘Big John’ Detained in Australia After Visa Dispute
ScamBodia: The Chinese Fraud Empire Shielded by Cambodia’s Ruling Elite
French PM Suspends Macron’s Pension Reform Until After 2027 in Bid to Stabilize Government
Orange, Bouygues and Free Make €17 Billion Bid for Drahi’s Altice France Telecom Assets
Dutch Government Seizes Chipmaker After U.S. Presses for Removal of Chinese CEO
Bessent Accuses China of Dragging Down Global Economy Amid New Trade Curbs
U.S. Revokes Visas of Foreign Nationals Who ‘Celebrated’ Charlie Kirk’s Assassination
AI and Cybersecurity at Forefront as GITEX Global 2025 Kicks Off in Dubai
DJI Loses Appeal to Remove Pentagon’s ‘Chinese Military Company’ Label
EU Deploys New Biometric Entry/Exit System: What Non-EU Travelers Must Know
Australian Prime Minister’s Private Number Exposed Through AI Contact Scraper
×