What we know about the Centaurus subvariant

By Natalie Warren 03/08/2026 3 min read 56 views

An emerging subvariant of Omicron, BA.2.75, has drawn attention online under the nickname “Centaurus.” Scientists and public health officials are closely watching this strain as it spreads across several nations. While social media has seized on the celestial name, the medical community is focusing on the genetic changes driving its rapid transmission.

The cosmic nickname

When SARS-CoV-2 first appeared in 2020, the world had only one known strain. As variants emerged, officials moved to standardize naming to prevent xenophobia. The World Health Organization assigned Greek letters to new variants, such as Alpha and Beta. The dominant strain globally is now Omicron, but scientists have identified numerous subvariants within this lineage in recent months.

BA.2.75, also referred to as Centaurus by some, gained traction after a single tweet caught the attention of researchers. Although the WHO has not yet classified BA.2.75 as a variant of concern, the European Centre for Disease Prevention and Control designated it a “variant under monitoring” on July 7, 2022. It has been detected in countries including the United Kingdom and Germany.

Experts first identified this lineage in India in May. Local reports suggested it was spreading faster than other Omicron subvariants at the time. Despite the speed, virologists emphasize that the number of genomic sequences available for analysis remains relatively small. Dr. Ulrich Elling, a research group leader at the Institute of Molecular Biotechnology in Vienna, explains that only about 400 genomic sequences of the variant have been made available so far. This limited data makes definitive conclusions difficult.

Genetic changes and immune evasion

The constant turnover of subvariants suggests the virus is now optimizing for transmission within populations that already possess some level of immunity. This evolutionary pressure changes the goal of viral spread from global dominance to efficient evasion of existing defenses, making predictors of future waves much less reliable than they were in earlier stages of the pandemic.

Dr. Elling notes that the variant possesses nine mutations. Eight of these are new, specifically located in the spike protein region, which the virus uses to enter human cells. This accumulation of changes suggests the virus is adapting to bypass immune defenses. Early research indicates that BA.2.75 has a higher affinity for ACE2 receptors, the entry point for SARS-CoV-2 in human tissues.

Dr. Elling states that immune evasion is the primary selective force acting on the virus. Because of this, experts expect BA.2.75 to affect primarily how well vaccines and prior infections prevent infection, rather than necessarily causing more severe disease. Several studies have explored the variant’s potential to escape antibodies. One preprint shared by a team in Japan tested how pseudoviruses carrying BA.2.75 spike proteins interacted with monoclonal antibody treatments. The results suggested the variant might resist some of these treatments, though the data comes from lab-generated models rather than live virus isolates.

Effectiveness against vaccines

Despite these concerns, existing data suggests vaccines remain effective against severe outcomes. A study published in The Lancet: Infectious Diseases in September 2022 compared BA.2.75 to the dominant BA.5 variant. The researchers found that BA.2.75 has approximately the same level of resistance to antibodies as BA.5.

Dr. Benjamin Murrell, an assistant professor at Karolinska Institutet, noted that current antibodies from vaccines or prior infection are likely effective at preventing severe symptoms. While the data is preliminary, it offers a degree of reassurance to the public. However, some virologists, like Spyros Lytras, remain cautious. He argues that while preliminary lab results suggest a different immune escape phenotype, there is not yet enough epidemiological evidence to label BA.2.75 a major threat.

Experts still cannot predict if BA.2.75 will become the dominant strain in upcoming waves. The virus can hide in immunosuppressed patients for extended periods before resurfacing. With Delta still present and the Omicron clade evolving rapidly, the coming months will likely bring further shifts in the dominant strain.