COVID-19: this is how Ómicron and its subvariants advanced around the world

The emergence of the Ómicron variant, which occurred in November 2021 in South Africa, caused alarm throughout the world. However, the sharp increase in infections in that and other countries in which it was found, was followed by a rapid decline. All, accompanied by cases that were mostly mild and did not cause collapse in health systems in most countries.

However, seen in retrospect, one of the features of the Ómicron variant of SARS-CoV-2 that most attracts the attention of specialists is that, from a genomic point of view, it consists of three distinct sublineages (called BA.1, BA.2 and BA.3) that seem to have emerged at about the same time, two of which advanced massively throughout the world.

That means that Ómicron had time to diversify before scientists detected him. Any theory about its origins must take this characteristic into account, as well as the number of mutations, according to Joel Wertheim, molecular epidemiologist at the University of California, San Diego.

Thus, so far, the World Health Organization (WHO) has recognized, in addition to the Alpha, Beta, Gamma and Delta variants prior to Omicron, the original BA.1 of the latter mutation, now predominant BA.2 worldwide, present in 86% of sequenced cases and responsible for the current ones outbreaks in Asia and Europe.

Also, BA.3 detected at the beginning of Ómicron and without epidemiological relevance to experts, and BA.4 and BA.5, which were included this week by WHO in those identified under surveillance, of which, although not much is known at the moment, caused some cases in South Africa, Botswana, the Kingdom United and Denmark between January 10 and March 30. The infections it generates seem to be quite similar to those caused by BA.2, according to the first observations.

Meanwhile, in its epidemiological update report of 29 March, WHO reported a new subvariant, which it qualified as a result of the combination between the original variant of Ómicron (BA.1) and the sublineage BA.2, also known as silent Ómicron. And he named it XE.

And while its rate of spread does not seem to be much different from BA.1, the latest data show that it would be 12.6% more transmissible than BA.2. All are considered to be of concern by the international organization.

Tedros Adhanom Ghebreyesus, head of the UN agency, reiterated the need to increase the number of tests and samples sequenced so that scientists can track existing variants and identify new ones as they emerge.

“There are currently a number of Ómicron lineages that we are following closely, including BA.2, BA.4 and BA.5 and another recombined that has been detected, consisting of BA.1 and BA.2,” he said.

Variants BA.4 and BA.5 have been reported in several countries, including South Africa and some European nations, reported the Organization's lead epidemiologist, Dr. Maria Van Kerkhove.

“So far there are less than 200 sequences available and we hope that this will change (...) We are following (the virus) very closely to see if there is any spike in case detection, but (so far) we haven't seen any changes in epidemiology or severity,” said the specialist.

COVID cases already exceed 500 million worldwide, because of BA.2?

On Thursday, 500 million cases of COVID-19 were exceeded worldwide, according to a Reuters account, as the highly contagious BA.2 subvariant of omicron increases in many countries in Europe and Asia.

The rise in BA.2 has been attributed to recent upturns in China, as well as the record number of infections in Europe. It has been called a “stealth variant” because it is somewhat more difficult to trace than others.

South Korea leads the daily average of new cases, registering more than 182,000 new infections a day and accounting for one in four infections globally, according to a Reuters analysis.

New cases increase in 20 of the more than 240 countries and territories tracked, including Taiwan, Thailand and Bhutan.

Shanghai is battling the worst COVID-19 outbreak in China since the virus first emerged in Wuhan in late 2019, with nearly 25,000 new local cases reported, although the city's quarantine policy is criticized for separating children from their parents and putting asymptomatic cases with who have symptoms.

“The prevention and control of the epidemic in Shanghai is at the most difficult and most critical stage,” Wu Qianyu, an official of the municipal health commission, told a briefing.

Meanwhile, in some European countries there is a slower increase in new cases, or even a decline, but the region continues to register more than one million cases every two days.

In Germany, the 7-day average of new infections fell and now stands at 59% of its previous peak at the end of March. New cases are also declining in the UK and Italy, while they remain stable in France.

In general, cases of COVID-19 in the United States have fallen sharply after hitting record levels in January, but the resurgence of cases in parts of Asia and Europe has raised fears of another wave in the North American country.

BA.2 currently accounts for about 86% of all sequenced cases in the world, according to the World Health Organization. It is known to be more transmissible than the BA.1 and BA.1.1 omicron subvariants. However, evidence obtained so far suggests that BA.2 is no longer likely to cause serious illness.

Although cases have skyrocketed in Europe and Asia recently, the United States remains the country with the highest number of COVID infections since the start of the pandemic, with 80.41 million, followed by India, with 43.04 million, and Brazil, with 30.14 million.

Since 2020, about 37% of the world's COVID cases have occurred in Europe, 21% in Asia, and 17% in North America.

According to the variant-tracking website Covariants.org, the Netherlands was close to the peak of its BA.2 wave when the subvariant reached 83% of infections, in the second week of March. Switzerland was also close to its peak of BA.2 when the subvariant reached 80% of infections in mid-March. After declining for weeks, cases in the UK had doubled from the lowest point of February 25 and would soon reach the peak of the BA.2 wave when the subvariant caused 88% of cases there, between 7 and 21 March.

The experience of BA.2 in the US is much more like what happened in South Africa. In the second and third weeks of February, when that subvariant was responsible for about 88% of transmission there, cases rebounded slightly, but then continued to decline during the month of March.

As Infobae doctor Roberto Debbag (MN 60253) observed before Infobae's office, “the world is experiencing moments of calm and unrest in relation to COVID”. “There is an effect that I call ping pong, which is given by the intensification of outbreaks in some regions or countries and the decrease in others and this is what happens now in China, that is, circulation of the BA.2 subvariant of Ómicron, in populations that perhaps with the vaccines they received are in a decline in immunity”, analyzed the expert.

Asked about whether such an intensification of the pandemic is possible in Argentina, he said: “I don't think so. And I think so because here we had an impact of the Ómicron BA.1 variant less than six months ago, which generated levels of natural immunity in the population that still persist.”

In addition, for him, “the high rate of vaccination in the country, even with a scheme in children, are other protective factors.”

In the same vein, according to Dr. Ian Lipkin, professor of epidemiology at Columbia University's Mailman School of Public Health, “the increase in the number of cases in China reflects a combination of factors: its population that is immunologically naive, that is, has not seen much of the virus in the past (NdR: because of the COVID zero strategy applied in that country) and at the same time they have not been effectively vaccinated to resist it.”

China mainly used Chinese-made Sinovac and Sinopharm vaccines. Both companies said their vaccines were more than 78% effective against COVID-19 in their preliminary trials, but later other studies suggested otherwise. Late stage trials of the Sinovac candidate in Brazil, for example, showed an efficacy rate of 50.38%, just above the WHO approval threshold.

Other studies suggested that the immunity of two doses of these vaccines decreases rapidly and that protection may be limited, especially among older people and especially compared to mRNA vaccines. Against Ómicron, studies found that all vaccines offer less protection.

Some future projections

All viruses change over time, and so does SARS-CoV-2. Most changes have little or no effect on the properties of the virus. However, some changes may influence some of them, such as their ease of spread, the severity of the associated disease, or the effectiveness of vaccines, drugs for treatment, diagnostic means or other public and social health measures.

WHO, in collaboration with partners, networks of experts, national authorities, institutions and researchers, monitored and evaluated 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, led to the beginning of the use of the specific categories of “variant of interest” (VOI) and “variant of concern” (VOC), in order to prioritize monitoring and research on a global scale, and ultimately instance, to guide the response to the COVID-19 pandemic.

The specialists also explained that as viruses mutate over time, recombinant variants are likely to be produced.

“It's happened a few times, and usually the way it happens is that when two variants circulate and someone gets infected with both at the same time, then the virus recombines with the characteristics of both variants.” Carlos Malvestutto is an infectious disease specialist at the Wexner Medical Center at Ohio State University, and in a recent interview he confirmed that, so far, there is no indication that the XE variant is better at escaping immunity obtained by a previous infection or vaccination. And she doesn't know if she'll be the last one to show up.

For Andrea Ammon, director of the European Centre for Disease Prevention and Control (ECDC) and Maria Van Kerkhove, from WHO, Ómicron will not be the last variant. The experts also said that “it is not certain that SARS-CoV-2 continues to mutate into milder strains that make people less sick than previous variants.”

In this regard, Professor Mario Clerici, professor of Immunology at Milan State University and scientific director of the Don Gnocchi Foundation, said: “None of us can say what will happen in the future. Especially since this is such a strange virus that it continually faces us with challenges. All we can say is to give clues as to what happened to any other virus.”

“In the history of man there have been at least six or seven jumps of coronavirus species from animal to man so far and SARS-CoV-2 is just the last. In all other cases, what happened was that after an acute phase, the virus became much milder. And all these coronaviruses, except MERS which, however, is another story, have always lived with us and give us symptoms that are very mild, very mild colds. So, if we are based on what happened with all the other coronaviruses, it is quite logical to assume, to expect, that the same thing will happen with this one too,” concluded the immunologist.

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