Coronavirus: Omicron subvariant BA.2 replicates faster in brain cells than other strains, study finds

A new study has found that Omicron subvariant BA.2, which was dominant worldwide early this year, replicates more swiftly than other strains in our brain cells. Further, this subvariant causes faster programmed cell death in human brains.

In this study, scientists from the University of Hong Kong and Chinese University of Hong Kong aimed to find out if, and how, Omicron sub variants behaved differently in their impact on brain cells, in comparison to earlier COVID strains.

The Hong Kong researchers developed cells in the laboratory that mimicked human brain cells. Then, they exposed these brain cells with the Omicron variants BA.1 and BA.2, as well as the earlier Delta strain and the original Coronavirus strain from the Wuhan outbreak at the start of the pandemic. The study findings were published in the science journal Nature.

In experiments on in vitro forebrain and midbrain cells, the researchers found that Omicron BA.2 replicated much faster than other strains. It was also found to induce a lower level of interferon than other strains. Interferon is a protein released by the human body as a defense mechanism against viral infections.

The scientists said that Omicron BA.2 triggered a substantially higher magnitude of programmed cell death upon infection of brain cells, compared to other strains.

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The researchers also observed new Omicron variants – BA.4.1 and BA.5.2 – to test their ability to replicate in human brain cells. Both BA.4.1 and BA.5.2 are offshoots of BA.2. The researchers found that BA.5.2 could replicate much faster than BA.4.

Omicron variants BA.5 and BA.4 have overtaken BA.2 in recent months. Further, BQ.1, which is a descendant of Omicron BA.5, is the dominant strain in the United States and some European countries.

“While most patients survived the infection, post-Covid-19 sequelae, including neurological manifestations, are common,” the researchers wrote.

“The increased efficiency of BA.2 to replicate and cause apoptosis [programmed cell death] in the brain organoids is alarming, indicating that the long-term consequence of BA.2 infection in the central nervous system (CNS) should be closely monitored,” they added.

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Another recent study using specialized MRI machines found that COVID can lead to significant changes in the brain in the long run. The brain scans revealed significant abnormalities, even six months after the patient’s initial COVID-19 infection.

The brain regions affected are found to be linked with fatigue, insomnia, anxiety, depression, headaches and cognitive problems. These abnormalities may explain problems like cognitive, anxiety and sleep issues, which several people are experiencing post COVID, which could also be interfering with their routine activities.