Two new subvariants of omicron are causing (again) a considerable increase in COVID infections in South Africa. Is about BA.4 and BA.5, which spread much faster than the original variant.
Scientists are still unclear if the new variants cause an increase in hospitalizations, what they are thinking is that these new waves of infection are establishing predictable patterns.
“These are the first signs that the virus is evolving differently compared to the first two years of the pandemic, when variants seemed to appear out of nowhere,” explains Tulio de Oliveira, a bioinformatician at Stellenbosch University, in South Africa.
Why are the new subvariants more ‘predictable’?
Oliveira’s research team analyzed viral genomes from clinical samples and found that BA.4 and BA.5 emerged to medicated December 2022 and early January 2022.
Lineages have been increasing ever since and now account for 60 to 75 percent of COVID infections in South Africa.
Jesse Bloom, a viral evolutionary biologist at Fred Hutch, a research center in Seattle, Washington, agrees that BA.4 and BA.5 are spreading faster than other omicron lineages.
“What is not yet clear is why they are more transmissible,” he says. Both are closely related to BA.2, though exactly how is unclear, adds Bloom.
BA.4 and BA.5 carry a key mutation called F486V at its spike proteins, the viral protein responsible for infection and the primary target of immune responses. Bloom’s team previously found that this mutation could help the variants dodge antibodies that block the virus.
Another study, published on the ResearchSquare preprint server and led by virologist Xiaoliang Xie of Peking University in Beijing, also found that antibodies triggered by BA.1 infection were less potent against BA.4 and BA.5. Moore says the results are also consistent with his unpublished experiments.
Will there be a new wave?
Although BA.4 and BA.5 have been detected in several European countries and in North America, it is Variants may not trigger a new wave of COVID-19 in these places, at least immediately.
The appearance of these strains suggests that the omicron lineage continues to improve by eroding immunityHo says. “It’s pretty clear that there are some holes in Omicron that are gradually being filled by these new sub-variants.”
If SARS-CoV-2 continues down this path, its evolution could become similar to that of other respiratory infections, such as the flu.
Earlier variants, including alpha, delta, and omicron, differed substantially from their immediate predecessors and all arose instead from distant branches on the SARS-CoV-2 family tree.