What are the variants of the coronavirus that are worrying the world today

The coronavirus pandemic continues. Yesterday alone, there were 573,000 new infections despite the fact that many countries lifted all restrictions and people hardly follow the issue with concern.

The 92,600 positives in Germany or the nearly 30,000 infected in the United Kingdom recorded just a day ago; plus the mass lockdowns taking place in China; or the general campaign in Japan, which is experiencing a resurgence with almost 50,000 infections in the last 24 hours, are concrete examples that SARS-CoV-2 continues to advance. Even though in many regions, such as ours, it seems that the pandemic is not perceived.

According to epidemiological data from all countries, the variant that circulates in the world today is Ómicron, which displaced Delta at the end of 2021. But health experts around the world are on the lookout for possible new, more contagious variants or subvariants that may appear.

“The emergence of new variants of the coronavirus occurs as a result of its ability to replicate, which does so billions of times and helps the virus to change its genetic characteristic and find ways to survive in a hostile environment,” the infectiologist and member of the Commission of Vaccines of the Argentine Society of Infectology (Sadi) Francisco Nacinovich (75,823).

Viruses such as SARS-CoV-2 are constantly evolving as changes in the genetic code (genetic mutations) occur during genome replication. A lineage is a group of genetically closely related variants of viruses derived from a common ancestor. A variant, meanwhile, has one or more mutations that differentiate it from the other SARS-CoV-2 variants.

As expected, multiple variants of the COVID-19 virus have been documented in the United States and globally during this pandemic. To inform local outbreak investigations and understand national trends, scientists compare the genetic differences of pathogens to identify variants and how closely they relate to each other.

The World Health Organization (WHO), in collaboration with countries, networks of experts, institutions and researchers, has been monitoring and evaluating the evolution of SARS-CoV-2 since January 2020. The emergence of variants that posed a greater risk to global public health, at the end of 2020, prompted the use of the specific categories of “variant of interest (VOI)” and “variant of concern (VOC)” to prioritize global monitoring and research, and ultimately , guiding the response to the pandemic.

“Global systems have been put in place, whose effectiveness is currently being strengthened, to detect “signs” of possible variants of concern and to assess them for the risk they pose to global public health. However, national authorities may choose to designate other possible variants of concern and interest at the local level,” says WHO in its latest weekly bulletin.

The strategies and measures currently recommended by WHO continue to work against variants of the virus detected since the beginning of the pandemic. It has been demonstrated in many countries with widespread transmission of worrying variants that social and public health measures, such as infection prevention and control, effectively reduce the number of cases, hospitalizations and deaths from COVID-19.

Variants of concern and interest

A variant of SARS-CoV-2 that meets the criteria to be defined as a “VOC” responds to one or more of the following respective changes of a Variant of Interest (VOI), to an extent that is significant to global public health

-Increased transmissibility or harmful change in the epidemiology of COVID-19

-Increased virulence or change in the clinical presentation of the disease

-Decreased effectiveness of social and public health measures or diagnostic tools, vaccines and available treatments

Currently, WHO classifies two variants as VOC: Delta (B1.617.2) and Ómicron (B.1.1529). And it classifies Alpha (B.1.1.7 - British), Beta (B.1.351 - South African) and Gamma (P.1 - Manaus) as worrying variants previously in circulation. Variants of concern or of interest that have been shown to no longer pose a significant additional risk to global public health compared to other circulating variants of SARS-CoV-2 can be classified as variants of concern or variants of interest previously in circulation.

To this end, experts, in collaboration with the Technical Advisory Group on the Evolution of Viruses, conduct a rigorous assessment of several criteria, such as the observed incidence or the relative prevalence of variants detected in sequenced samples over time and in different locations, the presence or absence of other risk factors and possible current implications for control measures.

“Member States should continue to monitor variants, including variants of concern or variants of interest previously in circulation, and report any increase in observed cases associated with these viruses. The change from worrying variant in circulation and variant of interest in circulation to variant of concern previously in circulation and variant of interest previously in circulation, respectively, reflects a sharp decline in their circulation, but the possibility that the circulation of these variants cannot be ruled out reclassified will increase in the future”, insists WHO in communicating.

New subvariants under surveillance

Any variant of SARS-CoV-2 that has changes in the genome that are suspected to affect the characteristics of the virus and appear to indicate that the variant may pose risks in the future, although there is no clear evidence of any changes it may cause in the phenotype or on the epidemiological characteristics of the virus and it is necessary to maintain monitoring and further study until further information is available.

That is why WHO watches the growth of several subvariants to see if they become other variants of the coronavirus. All versions of Ómicron are highly contagious, so the variant quickly displaced previous forms of the coronavirus, such as Delta. In addition, several studies found that BA.2 is even more transmissible than BA.1 or called the original Ómicron.

“The UK Health Safety Agency estimates that subvariant BA.2 is growing 80% faster than BA.1. Also in the United States, BA.2 seems to be on track to surpass BA.1 to become the dominant variant,” explained Dr. Leana Wen, an emergency room physician and professor of health policy at the Milken Institute School of Public Health at George Washington University's Milken Institute. The expert agreed that “the good news is that the BA.2 subvariant does not seem to cause a more serious disease than BA.1 ″.

According to the Centers for Disease Control and Prevention (CDC) BA.2 is currently responsible for one-third of US infections, yet COVID-19 cases have followed the declining pattern that marked the end of Ómicron's BA.1 increase. Dr. John Brooks, CDC's medical epidemiologist and medical director of COVID-19 response, said that while BA.2 related infections could increase, serious illnesses or deaths associated with the subvariant are unlikely to increase.

WHO is currently following two new lineages of the Ómicron variant (BA.4 and BA.5), whose “additional mutations need to be studied further to understand their impact on the potential for immune escape”. The UN agency is working with scientists to better understand their current spread, as well as any potential impacts they may have. So far, according to the data held by this agency, only a few dozen sequences of these variants have been reported in a handful of countries. These are the XD or Deltacron and XE lineages.

On January 7, Leondios Kostrikis, Professor of Biological Sciences at the University of Cyprus and head of the Laboratory for Biotechnology and Molecular Virology announced that his research group at the University of Cyprus in Nicosia had identified several SARS-CoV-2 genomes that had elements of the Delta and Omicron.

From that moment on they decided to name it “Deltacron” and Kostrikis, together with his team, uploaded 25 of the sequences to the GISAID public repository and, a few days later, added another 27. In just one day, the Bloomberg news outlet spread what happened and Deltacron quickly became international news.

Regarding XE, at the moment the first reports describe it as silent, highly contagious and with still unclear symptoms, the fact is that XE would be transmitted 10% faster than its predecessors and its speed of spread is still under study.

In viruses, as in any organism, random mutations occur, that is, alterations of the genetic material. Most of these mutations will have no effect, but others can modify the characteristics of the virus, they can even give it advantages.

Dr. Angela Rasmussen, a virologist at the University of Saskatchewan, in Canada, said that “there is no reason to be nervous”. He noted that XE is one of the many recombinants of Ómicron BA.1 and BA.2. “As such, as much as it succeeds, it will still be a sublineage of Ómicron.” Delta had more than 200 sublinages of this type before being displaced by Ómicron. He also noted that “XE is not a Greek letter that designates a new variant of interest. It's just a recombination of Ómicron, the fifth identified, after XA, XB, XC and XD.” He advised that the same precautions should be taken for COVID-19 in general.

WHO Director-General Dr. Tedros Adhanom Gebreyesus said that “it is gratifying to see a downward trend in recorded deaths (from COVID-19), which last week were the lowest in the last two years.” However, the head of the international health entity has repeated that the pandemic “is far from over”.

Transmission remains very high and vaccination coverage remains very low in too many countries and the relaxation of many social and public health measures is allowing transmission to continue, with the risk of new variants emerging, Tedros explained. He added that “COVID-19 is now affecting countries in very different ways.” In countries with high immunity from the population, there is a dissociation between cases, hospitalizations and deaths; in others with less access to vaccines, the massive increase in cases has resulted in a large number of hospitalizations and even more deaths compared to previous waves.

When the pandemic has just entered its third year, the director is concerned about three factors. Firstly, the fatigue of the population. Secondly, the duration of immunity arising from previous vaccination or infection remains unclear. And third, we cannot predict how the virus will evolve.

Despite uncertainties, he recalled that the world has the tools to limit transmission, save lives and protect health systems: “We have the systems to better understand the virus as it changes, and we have the vaccines, testing, treatment, and social and public health measures to end the acute phase of the COVID-19 pandemic,” the official concluded.

The most plausible scenario is that the virus continues to evolve, but that the severity of the disease it causes decreases over time as immunity increases due to vaccination and infection. The second possibility is the best-case scenario: the emergence of less serious variants against which boosters or new vaccine formulations are not required. However, the third scenario is the worst possible, the emergence of a more virulent and highly transmissible variant.

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