Vol.42  「Are COVID surges becoming predictable? Latest Omicron subvariants offer a hint」

Last Updated 27 May 2022. Cellspect Co., Ltd.

Due to the differences in mutations, several subvariants of Omicron have been discovered recently in the world. According to the monitoring of the U.S. CDC, the proportion of the subvariant "BA.212.1" of SARS-CoV-2 (COVID-19) Omicron subvariant BA.2 is rising to 36.5% by the end of April in the U.S. South Africa also reported new Omicron subvariants BA.4 and BA.5, which accounted for nearly 60% by the end of April. All three subvariants appear to have spread faster than the current global epidemic of BA.2, causing a new wave of increases in cases and hospitalizations in the United States and South Africa.

 

Outside South Africa, BA.4 and BA.5 have also been found in over 15 countries. Studies have shown that BA.4 and BA.5 may evade antibodies caused by the original Omicron virus, BA.1, and the researchers believe that BA.4 and BA.5 "may lead to new waves of infection." It is worth noting that BA.212.1, BA.4 and BA.5 all have the L452Q mutation, which is the key mutation site of the previous Delta, but the absence of this mutation in the original Omicron may give the virus more advantages in transmission and immune escape.

While there are still concerns over whether the unknown subvariants of the virus could render the vaccine ineffective and increase the number of infections, some scientists have recently suggested that the rise of these Omicron subvariants may mean that SARS-CoV-2 waves are beginning to settle into predictable patterns, with new waves periodically emerging from circulating strains. 

 

“These are the first signs that the virus is evolving differently,” compared with the first two years of the pandemic when variants seemed to appear out of nowhere, says Tulio de Oliveira, a bioinformatician at Stellenbosch University in South Africa. Previous variants, including Alpha, Delta and Omicron, differed substantially from their immediate predecessors, and all emerged, instead, from distant branches on the SARS-CoV-2 family tree.

Virologist David Ho at Columbia University in New York City said that the emergence of these strains suggests that the Omicron lineage is continuing to make gains by eroding immunity. “It’s pretty clear that there are a few holes in Omicron that are gradually being filled up by these new subvariants”, said Ho. If SARS-CoV-2 continues along this path, its evolution could come to resemble that of other respiratory infections, such as influenza. In this scenario, immune-evading mutations in circulating variants, such as Omicron, could combine with dips in population-wide immunity to become the key drivers of periodic waves of infection. It is probably what we should expect to see more and more of in the future.

In fact, in addition to SARS-CoV-2, there are four other coronaviruses that are already circulating in the population. According to research in Europe and the United States, about 1 in 10 people who have flu symptoms during the flu season each year actually get the coronavirus, not the flu virus, so the coronavirus has long been in our lives. As for when the COVID-19 virus will become the fifth "normal" virus to persist in the human population for a long time, it may ultimately depend on our means. It is believed that when the virus becomes predictable and controllable, humans can coexist peacefully with the virus.

 References:​​

  1. Carolyn Crist, May 4, 2022, “Latest COVID Subvariants Create New Waves, Evade Immunity”. Medical Device Network

  2. Ewen Callaway, May 6, 2022, “Are COVID surges becoming more predictable? New Omicron variants offer a hint”. Nature.

  3. Houriiyah Tegally et al., May 2, 2022. “Continued Emergence and Evolution of Omicron in South Africa: New BA.4 and BA.5 lineages” medRxiv

  4. Xiaoliang Xie et al., May 2, 2022. “BA.2.12.1, BA.4 and BA.5 escape antibodies elicited by Omicron BA.1 infection” bioRxiv

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