As countries wait for cases to subside COVID-19 called the Omicron or BA.5 variant, researchers around the world are looking for what’s next.

A subvariant of this Omicron under the name BA.2.75 or “Centaur” grew rapidly in India. Some scientists are sounding the alarm, while others say the variant is unlikely to become widespread. A paper recently published in the prestigious international scientific journal Nature presents the relevant data.

Professors of the Faculty of Medicine of the National and Kapodistrian University of Athens Theodora Psaltopoulou (Professor of Internal Medicine-Epidemiology-Preventive Medicine), Stavroula (Lina) Pashu (Associate Professor of Endocrinology), Evangelos Terpos (Professor of Internal Medicine-Hematology), Thanos Dimopoulos (Professor of Internal Medicine-Hematology-Oncology and Rector EKPA) and Yiannis Trougakos, Professor of the Department of Biology at the National and Kapodistrian University of Athens, summarize the main points of this article.

The subvariant BA.2.75 or Centaur has been found in over 20 countries worldwide but is growing rapidly mainly in India. Since May, researchers have sequenced more than 1,000 samples of this variant. Data show that approximately two-thirds of new cases in this country are now due to BA.2.75. This variant had a powertrain advantage over the BA.5.

A series of studies have shown that two variants, Omicron 5 (BA.5) and “Centaur”, have approximately the same ability to evade the immunity provided by infection and vaccination. This suggests that Centaurus may not lead to a significant increase in disease rates outside of India, at least while population immunity is high and before the variant shows many additional mutations.

So far, BA.2.75 has been found at relatively low rates outside of India, in countries such as Japan, the United States and the United Kingdom, which are in the middle or just past peaks driven primarily by BA.5 . We are approaching a point where these options somehow compete with each other and are almost equivalent. Thus, people with BA.5 are unlikely to be seriously infected with BA.2.75 and vice versa.

Laboratory studies published more recently (mostly in the form of preprints) support this idea. Indeed, the two variants have a similar ability to avoid antibodies elicited by vaccination and prior infection.

In 2021, there was an explosion of cases in India caused by a Delta variant that shares a major mutation with BA.5. Presumably, previous Delta infections provide additional protection against BA.5, leaving a margin for BA.2.75. It is anticipated that some countries may have a different composition of Omicron executives than other countries.

Based on data in India, the Centaur variant does not yet increase hospitalization or death rates there. The combined effect of high levels of vaccination and prior infection certainly helps. This hybrid immunity will protect and largely keep people out of hospitals.

But while BA.2.75 is not yet widely adopted, it may be in the future. Some of the BA.2.75 sequences include a mutation found in BA.5 called L452R, which unfortunately can increase the subvariant’s ability to re-infect. Even if hospitalization and death rates remain low in the wave caused by the Centaurus variant, the high frequency of new waves of infection could mean more people with long-term COVID-19 (i.e. strain on healthcare systems worldwide.

Source: APE/MEB