Strain "Omicron" with the prefix "Stealth": what is known about the new "invisible" variation

Irina Mishina

A variety of strain "Omicron" BA.2, or "Stealth" spreads fastest in Denmark. In addition, "Stealth" has already been detected in more than 60 countries of the world, including the USA, Australia, South Africa, India and Europe. Research by Danish scientists has shown that this version of Omicron is not just more contagious. It can infect vaccinated and recovered patients even more and faster, bypassing antibodies. According to Mikhail Bolkov, an employee of the Department of Immunochemistry at the Ural Federal University, the virus mutation occurred in the ORF3a protein and is used by the virus to move inside the cell. This led to the fact that the virus became better at deceiving the cell.

“The Stealth variant of Omicron is already starting to dominate. To begin with, a few explanations: 2 varieties were identified in the Omicron strain: the original BA.1 variant and the BA.2 variant - “Stealth”, or “invisible”. This variant is so named because it bypasses antibodies, and often "Stealth" is not visible in PCR tests. Compared to its predecessor, Stealth is even more contagious, but its pathogenicity is about the same. Now this variation of "Omicron" is rapidly spreading, displacing all previous strains. But I repeat: in terms of pathogenicity, this strain cannot be called more dangerous”, - said molecular biologist and virologist, Corresponding Member of the Russian Academy of Sciences Petr Chumakov to NI.

So far, preliminary data show that the BA.2 option is spreading 10-30% more actively than the classic Omicron. Those infected with Stealth have also developed new symptoms.

“The Stealth variety of Omicron is similar in its manifestations in adults under 60 years of age to the previous variety of this strain. According to the symptoms, these are sore throats, lesions of the upper respiratory tract, back pain, severe sweating. Sometimes the disease goes away without symptoms of SARS, but is accompanied by headache and insomnia. In most cases, there is no damage to the lungs, the upper respiratory tract is affected. Serious complications are not observed. But in the age category over 60, the risks of a severe course of the disease with Stealth remain. The danger of "Omicron" in general is that it bypasses antibodies. They talk about "cellular memory" in those who have been ill, but after 60 this does not always work, so the risk of a severe course even in those who have been ill and vaccinated in this age category remains. There are hospitalizations, but not more often than with the Delta strain. Children have a different clinical picture. The respiratory tract and gastrointestinal tract are affected, the lymph nodes become inflamed, sometimes the symptoms are similar to appendicitis. In children younger than 6 years old, it is not pneumonia that occurs, but bronchiolitis, inflammation of the small bronchi", - says Yevgeny Timakov, Ph.D.

Also, experts from the National Health Service of England reported that early symptoms of stealth omicron are fatigue and dizziness. According to doctors, dizziness can come and go during the day. If persistent fatigue accompanies this symptom, it indicates the need to get tested for COVID-19 and see a specialist.

The question arises: how to protect yourself from Stealth? Researchers from Denmark write that Stealth, better than all previous strains, leaves the immunity of those vaccinated and recovered. At the same time, there is evidence that those vaccinated and infected are less likely to spread the virus. But those who are not vaccinated, who have caught BA.2 ("Stealth"), become more contagious to others.

"All varieties of Omicron are breakthrough, that is, they bypass antibodies. It happens that someone who has been ill with a variety of Omicron BA.1 then becomes infected with Stealth, another variety of Omicron. All varieties of Omicron are super breakthrough. But those who has immunity as a result of vaccination, retains a chance for a milder course of the disease.We will get sick of everything.Now the Gamaleya Research Center said that they did not find children aged 6 to 11 in Moscow who would never have encountered coronavirus, therefore the protocol for clinical trials of the Sputnik M vaccine for this age group will have to be changed. It is not advisable to vaccinate those who have been ill with the Delta strain, in my opinion", - says Yevgeny Timakov.

“There is no need to panic. I compared the severity of the strain "Delta" and "Omicron". Strain "Delta" for 7 months from June to November of last year, 106 million people became infected and fell ill. 1 million 734 thousand people died, that is, 1.6% of the number of cases. As for Omicron, from December to mid-February, in 2 and a half months, the number of infected people reached 141 million people. Of these, 382 thousand people died, that is, 0.3%. We see that with an increase in the number of infections, mortality has decreased very significantly. This gives hope that the worst is over. You just need to comply with anti-epidemic measures”, - Professor Anatoly Alshtein, Doctor of Medical Sciences, told NI.

The first results of studies by Danish scientists show that with the spread of the Stealth variant, the proportion of hospitalized patients is not higher than with the classic Omicron variant. The percentage of deaths has not yet increased significantly either.

Recently, doctors are increasingly talking about such a sad consequence of covid as Alzheimer's disease.

“Those who have recovered from Alzheimer’s disease do have a risk of developing. This virus tends to affect the Central nervous system, which is confirmed by the loss of taste and smell. More serious damage to the central nervous system may also occur”, - says the infectious disease specialist, chief physician of the medical center “Leader-Medicine” Yevgeny Timakov.

“ COVID-induced brain changes show parallels with Alzheimer’s disease. The findings may point to a mechanism of "brain fog" in which memory and cognition problems occur in people with a long course of COVID. The study found that the brains of COVID-19 patients had some of the same pathological changes seen in Alzheimer's disease, which may explain the memory problems in survivors. But much more research needs to be done before we can draw more definitive conclusions”, - says Olga Mazurenko, most.doctor’s service's doctor.

But there is also good news. The Gamaleya National Research Center for Epidemiology and Microbiology received permission to conduct clinical trials of a drug for coronavirus based on monoclonal antibodies. Deputy head of the Gamaleya Center, Denis Logunov, stated that the drug is in a high degree of readiness, animal experiments have shown that it provides 100% protection. Head of the NIC Gamalei Gunzburg believes that the drug based on monoclonal antibodies is also effective against the Omicron strain.

Previously, the head of Gamaleya center Alexander Gintsburg spoke about the trials of a nasal vaccine against COVID-19. According to him, more than 50 volunteers who take part in the study of the drug have already been vaccinated. He said that they had no complications.