Covid -19 appeared a new strain of Omicron in Vietnam: The spread was many times higher than the old ones

BA.5 and BA.4 are two common strains in new cases in many Western countries. It is said to be many times more contagious than Omicron's BA.2.

At the meeting to provide medical information on the afternoon of June 27, Prof. Dr. Phan Trong Lan, Director of the Department of Preventive Medicine, Ministry of Health, said that Vietnam has had the penetration of the BA.5 variant of Omicron.

According to Mr. Lan, when a new strain enters, we will face the risk that they will overwhelm the old one. However, this is inevitable when people exchange and travel in the new normal. Through some small initial assessments, the BA.4 and BA.5 strains are more likely to spread faster than the previous BA.1 and BA.2.

In European and American countries, BA.4 and BA.5 are the two culprits that make them face a series of new Covid-19 waves. In the US alone, these are two strains accounting for more than 21% of new cases, as of June 11

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What is the BA.5 variant?

Just a few weeks after the BA.2 subtype caused a wave of new cases globally, two other sub-variants of Omicron also continued to spread to dozens of countries. These are two strains discovered by experts in South Africa in January, which have the ability to spread more strongly than BA.2. Then, in early April, it appeared in the US and gradually dominated the new cases.

But so far, according to the journal Nature, BA.4 and BA.5 seem to cause fewer deaths and hospitalizations. This sign also shows that the increasing immunity of people helps to overcome the immediate consequences of the increase in Covid-19 cases.

BA.4 and BA.5 carry their own unique mutations, with changes in the L452R, F486V mutations on the spike protein. This helps the virus stick to host cells faster, more easily, and may even modulate some immune responses.

A study in May found that BA.4 and BA.5 share a common origin with earlier strains of Omicron. However, another unpublished analysis suggests that these are two sub-branches of BA.2. The work was carried out by evolutionary geneticists Bette Korber and William Fischer at Los Alamos National Laboratory, New Mexico, USA.

Dr. Korber and Fischer also discovered that many genome sequences classified as BA.2 in the public database are actually BA.4 or BA.5. As a result, researchers may be underestimating the continued proliferation of strains, as well as the variety of mutations they produce.

Is the appearance of BA.5 dangerous?

The transmission advantage of mutations could result from biological changes, such as the rate of infection, that allow the virus to infect more people, faster.

According to epidemiologist Christian Althaus, University of Bern, Switzerland, the increase in BA.4 and BA.5 seems to stem from the ability to infect people who already have immunity to the predecessor and mutant Omicron strain. before. Most countries outside of Asia have very few measures to control nCoV. Therefore, an increase in BA.4, BA.5 cases is inevitable.

Professor Marc Johnson, University of Missouri, USA, said that all three sub-variants have a mutation to distinguish them from the old version of Omicron. This suggests that there is convergence in how the "descendant" strains overcome the immune system.

According to Professor Paul Bieniasz, Rockefeller University, USA, newer versions of Omicron can overcome antibodies produced by vaccination or previous illness. This means they will be re-infected, even multiple times, and over short periods of time. Preliminary findings suggest that the risk of BA.4 and BA.5 to global health "is likely to be greater than that of BA.4 and BA.5." original BA.2".

What future for us?

Omicron infection induces a weaker immune response and it is likely to rapidly weaken compared to previous strains. From an immunological perspective, a mutated infection is not very protective against infection with another strain, making it very likely that we will get it again after 3-4 months.

The good news in the current situation is that most people who get sick do not become seriously ill. At least at this point, nCoV still has no way to completely overcome the immune system.

But what is more worrying now is that every time Covid-19 is infected, there is a risk of sequelae for the patient. They have to live with a range of symptoms that can persist for months or years. It is too early to know how often Omicron infection leads to post-Covid-19 infection, especially in vaccinated people.

Other experts say that to keep up with the development of the virus, the Covid-19 vaccine should be updated faster, even faster than the annual flu vaccine. Virologist Kristian Andersen, Scripps Research Institute in San Diego, USA, shared: "Every time we think we have overcome the pandemic, are winning against the virus, it has new tricks. We don't. You can control it by getting everyone sick and hoping for better things to come."

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