Omicron, the 9th Variant in the Covid Puzzle
Variants have characterized the new phase of the pandemic waves in 2021, though many have been present since 2020.
The WHO has classified variants in two different categories: VoI and VoC, or Variants of Interest and Variants of Concern. With VoI, we mean a new, emerging variant, whose medical and public health relevance is not yet known, but worthy of interest. When the variant’s relevance becomes known, and is thought to be more contagious, cause severe symptoms, or may impact the vaccine-induced immune response, then it is classified as “of concern” (VoC).
Faced with a Variant of Interest, the WHO carries out a comparative assessment of its characteristics with respect to the variants already present, evaluating the risks to public health. At the end of this analysis, if necessary, laboratory investigations are carried out. In parallel, a review of the global epidemiology of the variant takes place, monitoring its global spread. In the case of a Variant of Concern, a comparative evaluation with respect to the other VoCs present is carried out, and in addition the Technical Advisory Group on Viral Evolution is consulted. If deemed necessary, further laboratory investigations take place in cooperation with WHO member states. After the analysis, the new classifications are communicated to the public, asking them to follow the guidelines drawn up at the beginning of the pandemic, and integrating them if necessary.
At the moment, WHO has 8 variants — 4 classified as Variants of Interest and 4 as Variants of Concern. Starting with VoI, we have Eta (B1.525), Iota (B1.526), Kappa (B.1.617.1) and Lambda (C.37), characterized as follows:
- The Eta variant, which appeared in late 2020 in several countries, is characterized, similar to Alpha and Beta, by mutation of the E484 spike protein, leading to a moderately lower efficacy of vaccine-induced immunization and available treatments.
- Kappa, which has increasing cases in Italy along with Delta, has shown moderate ineffectiveness of antibody treatments.
- Finally Lambda, first detected in Peru in late 2020 and recently recognized as VoI in June 2021, has caused many deaths in Peru. In the face of a recognized increased viability, doubts remain about the actual severity of the mutation, considering that the effects in Peru have affected a health system not comparable to Western standards.
It is no coincidence that symptomatology was barely mentioned in these four VoIs. As a VoI, the medical effects and risk rates on the individual are still unknown, and are under evaluation.
The following variants are currently recognized as VoC: Alpha (B1.1.7), Beta (B.1.351, B.1.351.2, B.1.351.3), Gamma (P.1, P.1.1,P1.2) and Delta (B.1.617.2, AY.1, AY.2):
- Alpha, identified in late 2020 in the United Kingdom, has a 50% higher viability than the original strain, with a moderate increase in the severity of symptoms, unchanged in their manifestation and increased risk of death.
- As for Beta, although the symptomatology is unchanged, there is a 50% increase in transmissibility, with significant resistance to antibody treatments.
- The Gamma mutation, also known as the Brazilian variant, is classified as VoC because of the possibility of reinfection and its increased transmissibility. At the moment, unfortunately, it is not possible to quantify the possible severity in the symptomatology.
- Finally, Delta, well known in Italy and identified for the first time in India, includes three different mutations of the spike protein (E484Q, L452R and P681R) and includes higher viability, together with the possibility of reinfection after a first infection with Sars-CoV-2. In the latter case, the symptomatology is milder than normal, resembling more a flu-like form.
About a month after the first reports in South Africa and other southern African states, the Omicron variant of the coronavirus is now present in at least 70 countries and is showing rapid spread, leading to thousands of new infections in the countries where it is most prevalent. The variant is contributing to new waves in Europe, particularly in the United Kingdom and Denmark, where there is more testing for Omicron and thus more reliable data. It is difficult to determine with certainty whether Omicron causes milder symptoms than do other variants. Data available so far are fragmentary, partly because there is a time lag between the time of infection and eventual hospitalization, which indicates an illness with severe symptoms.
Preliminary data on some studies and analyses conducted in South Africa have indicated a lower rate of Omicron hospitalizations when compared with those due to other variants of the coronavirus. Last week, Discovery Health, one of South Africa's leading private health insurers, indicated that the risk of hospitalization is 29 percent lower among people with Omicron than among those infected with other variants. Encouraging was Moderna’s recent announcement that it has detected the ability of its vaccine to successfully counteract Omicron after a third dose.
Faced with this picture of nine variants recognized thus far by the World Health Organization, there are twelve additional variants under evaluation that could fall into one of the two categories listed. Among these, it is worth mentioning the Epsilon variant, made famous with the "Majorca case." It will become a Variant of Interest once it has been ascertained that, despite its ability to penetrate the immune system, it does not involve, for the moment, greater severity and concomitant risk of death.
As far as we know, the creation of a variant, and then the mutation of the spike protein, occurs once the virus circulates in the body. That means that while these are the variants that have been recognized thus far by the World Health Organization, the list is destined to grow until the greater goal of global vaccination is reached.
