[Medicalnewstoday] Omicron: What do we know about this ‘stealth variant’?


A new version of the Omicron variant of SARS-CoV-2, called BA.2, appeared. Although experts are uncertain about its effects, they do know that it is spreading rapidly and that there are more than 20 regional variants that most COVID-19 vaccines target.

Should we worry about the ‘stealth variant’ of Omicron? Image source: Geraghty/The Sydney Morning Herald via Getty Images

Scientists first identified the BA.2 subvariant of Omicron in India and South Africa in late December 2021. Since then, it has spread to several countries, including the United States, United Kingdom, and the United States. Great Britain and Israel.

The virus has also spread rapidly in Denmark, increasing from 20% of all COVID-19 infections in the country in week 52 of 2021 to 45% by the second week of 2022.

Despite rapid domestic spread, initial analyzes showed no difference in hospitalizations between the subvariable BA.2 and the original form of Omicron, also known as BA.1.

However, studies are still underway to understand how infectious BA.2 is, along with how effective vaccines against it are.

Although BA.2 is not currently a “variant of concern”, public health officials in the UK have taken an interest in how widespread it is to designate it as a “variant under study”. “.

To understand more about the emerging extra variable, Medical News Today spoke with six experts in public health, immunology and infectious diseases.

The rapid spread of Omicron

Dr. Donald C.Vinh, associate professor of the Faculty of Medicine at McGill University, Canada, told MNT : “Omicron has three main “subvariants” – BA.1, BA.2 and BA.3 – according to the World Health Organization (WHO).”

“So far, the majority of Omicron cases have been BA.1. However, in some places, BA.2 has emerged and spread faster than BA.1,,” he continued, emphasizing.

Amesh A, Adalja, senior scholar at the Johns Hopkins Center for Health Security, told MNT : “This sister variant, still Omicron, is interesting because it seems to be replacing Omicron in some parts of the world. There is speculation that it may be more contagious than its sister.”

How the rapid spread of the subvariable BA.2 may affect public health is still under investigation.

Dr. Richard Reithinger, Ph.D., president of global health at RTI International explains: “The SARS-CoV-2 Omicron variant is interesting to scientists because of its relatively higher number of mutations, […] allowing it to partially evade the human immune response; higher transmissibility and pathogenicity, i.e. higher ability to cause and effect disease; and lower virulence, which means a lower likelihood of serious illness.”

“The big question for newly identified variants and subvariants like Omicron BA.2 is how these three characteristics are different from the original SARS-CoV-2 virus variant or the Omicron variant. And why is there such a difference?”

“If some countries are currently reporting an increase in infection rates of the BA.2 subvariable, is it because additional mutations make it more transmissible or allow it to evade the immune response? easier than other Omicron sub-variants? Does BA.2 cause the same clinical pathology as the Omicron maternal variant (B.1.1.529) and the offspring (BA.1 and BA.3)? Also, what are the current vaccine and treatment options against BA.2? ”

According to Dr. Reithinger, these are some of the questions that public health professionals must consider while monitoring this secondary variable.

What do we know so far about Omicron?

While researchers are still gathering data on how BA.2 might affect the general population, laboratory studies have verified many of its molecular properties.

Anna Ssentongo, assistant professor of public health at Penn State University School of Medicine “BA.2 lacks the 69-70 mutant, so it does not cause S gene targeting failure, making identification more difficult in PCR assays. Because of this, BA.2 is nicknamed the ‘stealth variant’.

Dr. Ssentongo added that BA.2 has more than 20 mutations in its mutant protein, which is the target of many COVID-19 vaccines because the virus uses it to enter healthy cells. Although this difference may make BA.2 more resistant to the vaccine, more research is needed to confirm any effects.

“Similar to its parent lineage (Omicron), it is believed to be highly transmissible and less likely to cause disease than Delta or Beta variants, especially if a person is fully vaccinated. and – even better – enhanced. Ultimately, however, this will have to be confirmed by ongoing clinical and laboratory studies, which are expected to provide results in the next few weeks.”

Dr. Reithinger added.

Dr. Donald C.Vinh agrees that before drawing conclusions about how the secondary variable may affect public health, further research is needed: “It is important to mention that there are very few data on clinical differences between BA.2 and BA.1. Specifically, we don’t have solid data to know if BA.2 is more contagious, leads to more severe disease, or can evade immunity better than BA.1. However, early data from Denmark and the UK suggests that BA.2 may be more contagious than BA.1. “

Should we be worried?

When MNT asked whether we should worry about BA.2, Dr. Pavitra Roychoudhury, research associate in the Division of Vaccines and Infectious Diseases at the University of Washington, explains: “It remains to be seen how BA.2 will compete with circulating viral disease, and also whether it will cause more severe disease. We will continue to monitor the frequency of BA.2 through the use of genomic monitoring. ”

Dr Adalja agrees that much remains to be seen: “We know that this is a variant that has been around since the early days of Omicron and that it has some similar mutations and some differences. At the moment, it is not clear whether it is more transmissible. It may have similar characteristics when it comes to vaccine effectiveness and severity.ask for. It’s too early to know what role BA.2 might play. It is likely that it will only be part of the Omicron wave and they stretch it over time and eventually become the dominant version of the Omicron. More research is needed.”

However, Dr. Barton F. Haynes, director of the human vaccine institute in the Department of Medicine at Duke University School of Medicine, said that because of its molecular changes, there may be cause for concern about BA. 2.

“We are concerned that because it is so different from Omicron BA.1 it could escape current vaccines and neutralizing antibodies to Omicron BA.1. Up to this point, we are studying the Omicron BA-2 virus to see if current vaccine-neutralizing antibodies neutralize it.”

“Whether BA.2, or any other Omicron subvariant or other SARS-CoV-2 variant, there is indisputable evidence that currently available vaccines are quite effective in protecting people against infection and is highly effective in protecting people from developing severe illness or – worst case scenario – dying from SARS-CoV-2 infection, ‘ Dr. Reithinger explained.

“In addition, even with vaccination, people should consider adhering to non-pharmacological interventions, such as masks, physical distancing and hand washing, especially when in crowded environments. casting and/or highly transmissible,” he recommended them.

Original link: http://www.medicalnewstoday.com/articles/omicron-what-do-we-know-about-the-stealth-variant#Should-we-be-concerned?

The article is translated and edited by ykhoa.org – please do not reup without permission.

Translator: BS. Kieu Trinh

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