The scientific journal “Nature” presented through five questions and answers what is known so far about the two new members of the “family” of Omicron.
THE Ομικρον is back – like a good “sequel” to a Hollywood movie! – thanks to the two new even more contagious ones sub-variations of ΒΑ.4 and ΒΑ.5which now seem capable of infect more easily with coronavirus even vaccinated people who had better immunity to previous subtypes of Homicron or other variants of the virus.
Less than a few weeks have passed since the worldwide wave of infections caused by Omicron 2 (BA.2) and two new “branches” of the same variant are constantly gaining ground internationally. They first appeared again in South Africa and have since been detected in dozens of countries.
The first signs are that both transmitted faster than previous Omicronsbut – so far at least – the new increase in cases has not been accompanied by a corresponding increase in hospitalizations and deaths, an indication that the population has acquired a degree of immunity either due to vaccination, or due to previous infection, or both (hybrid immunity ).
The scientific journal “Nature” presented through five questions and answers what is known so far about the two new members of the “family” of Omicron and what they may mean for the evolution of the Covid-19 pandemic.
What are BA.4 and BA.5?
The two new sub-variants are more similar in Omicron 2 (BA.2) than in the original (BA.1). But they carry their own unique mutations, including changes (called L452R and F486V) in the virus’s protein spike, possibly facilitating both its binding to human cells and its resistance. It is possible that BA.4 and BA.5 are derived from Omicron 2, while scientists also consider it possible that many genome sequences classified as Omicron 2 in public genetic databases are actually BA.4 or BA.5 . If this is indeed the case, then scientists may have underestimated the evolution of the two new variants.
Why are new variants gaining ground worldwide?
Usually the advantage of a virus is that it has undergone biological changes that allow it to infect more people more quickly. In the case of BA.4 and BA.5, it seems that their spread is mainly due to their ability to infect people who were immune to previous forms of Omicron and other variants of the coronavirus.
The computer biologist Christian Althaus of the Swiss University of Bern estimates that the size of the new wave of NE4 and NE5 will vary from country to country and “may be 5% in some countries and 30% in others. “Everything will depend on the immunity profile of each country.” Countries have distinct immune profiles because they differ in both the history of Covid-19 waves and the vaccination rate of their population.
What impact will NE.4 and NE.5 have on society?
And that will probably vary from country to country. For example, despite the many new cases, South Africa has seen only a small increase in hospitalizations and deaths during the new wave of NEs 4 and 5. But other countries seem to be more affected. In Portugal, for example, where vaccination rates and booster doses are very high, the incidence and mortality rates are now similar to those of the first Omicron wave (although much lower than in the Delta and other variants). One possible explanation is Portugal’s demographic profile and the large percentage of older people who are more vulnerable to serious illness, according to Althaus.
How well do vaccines work against new subtypes?
Laboratory studies show that antibodies after vaccination are less effective against BA.4 and 5 than against previous Omicron subtypes such as BA.1 and 2. This makes vaccinated (even booster) more effective. vulnerable to multiple Omicron infections. Even people with hybrid immunity produce antibodies that are difficult to neutralize BA.4 and 5.
What will follow?
Everyone can make their own guess. The “parade” of Omicron variants is expected to continue, with new ones dealing new blows to existing immunity. “No one can say that BA.4 and 5 will be the last sub-variations. “It is highly likely that additional Omicron variants will occur,” said Kay Sato, a professor of virology at the University of Tokyo.
Another possibility, according to Cambridge University virologist Ravindra Gupta, is the emergence of a variant of a different branch (not Homicron) of the SARS-CoV-2 coronavirus family. Persistent Omicron infections can eventually create widespread immunity to it, opening a “window” for a completely different variant.
But according to other scientists, the longer the Omicron’s “family” continues to dominate, the less likely it is that a completely new variant of chronic infection will emerge. Scientists also have no guarantee that any subsequent variant will be less deadly, as, according to Sato, viruses do not necessarily evolve to become less lethal.
It is also unclear when a new variant will appear. NEs 4 and 5 appeared in South Africa only a few months after NEs 1 and 2, something that was repeated in other countries such as Britain and the USA. After all, it is always possible that the new coronavirus will have the fate of the other four mild seasonal coronaviruses that usually peak in winter like the flu and re-infect humans every three years or so.
The big question, according to Althaus, is whether the symptoms of Covid-19 will become more and more mild and whether the long Covid-19 will develop into a serious public health problem.
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