Covid variants, the complete list. The more the virus is allowed to run, the greater the risk of new mutations forming, potentially capable of at least partially evading the immunity given by vaccines or previous infections
If we were to complete the Greek alphabet, 9 would be missing, up to Omega, but the hope – whispered for now – is that we can stop at Omicron, or at worst Pi. Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO), hinted that there is no need to exaggerate with optimism: the conditions remain ideal for further variants of the coronavirus to develop
he said, and it is dangerous to assume that we are in the final phase, however it is possible that the acute phase of the pandemic will end this year if some key objectives are achieved. For instance vaccinate 70% of the population of each country by mid-2022, with a focus on people who are at greatest risk for severe Covid, increase test levels and sequencing. Just to say, in Africa only 11% of the population is fully vaccinated.
Evasion of immunity
Two years of pandemic have taught us that the more the virus is allowed to “run”, the greater the risk of new variants forming, potentially capable of at least partially evading the immunity given by vaccines or previous infections. When a virus replicates it can modify itself, giving rise to mutations in its genome: this is especially true for those with RNA (such as coronaviruses). If the new version begins to spread, for example for greater transmissibility or the ability to circumvent the previously acquired immunity, a new one is identified “concern” variant (You, variant of concern). Sars-CoV-2, monitored constantly around the world, has produced hundreds of variants of itself, but most of the mutations do not have a significant impact on the pandemic course. Here are the variants recorded and those that have raised the greatest alarm.
Alpha (B.1.1.7), identified in the UK in September 2020
It has a higher transmissibility than the original strain (Wuhan strain), which results in an absolute greater number of infections and a consequent increase in severe cases. The Alpha variant has been “downgraded” by the WHO (so it is no longer a “concern variant”), because its circulation has drastically reduced with the emergence and spread of Delta. The characteristics of Alpha are increased transmissibility and severity of the disease, while the impact on the immune response is similar to that of the Wuhan strain (therefore the protection offered by vaccines and previous infections is optimal).
Beta (B.1.351), identified in South Africa in September 2020
Although it does not seem characterized by a greater transmissibility, this variant could induce a partial effect of immune escape against vaccine-induced antibodies and some monoclonal antibodies. Beta is still classified as a “concern variant”: it has a higher transmissibility than Alpha and causes a more severe disease.
Gamma (P.1), identified in Brazil in December 2020
Studies have shown a potential for increased transmissibility and a possible risk of reinfection. Gamma is still classified as a “variant of concern”: it gives more severe forms of Covid than the previous variants and a capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection.
Delta (B.1.617), identified in India in December 2020
It is characterized by a transmissibility 40 to 60% higher than the Alfa variant and is associated with a relatively higher risk of infection in unvaccinated or partially vaccinated individuals. Delta is still classified as a “variant of concern”: it has increased transmissibility and severity of the disease and a capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection.
Epsilon (B.1.427 / B.1.429), identified in the United States as of September 2020
It is one of the variants “downgraded” by the WHO (as Alpha), because its diffusion is extremely limited. It is not clear whether it has increased transmissibility or causes a more serious disease than the previous variants, while it has been shown to partially escape immune protection.
Zeta (P.2), identified in Brazil in January 2021
It is one of the variants “downgraded” by the WHO. It is not clear whether it has increased transmissibility or causes more severe symptoms, but certainly, like the previous ones, shows a capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection.
Age (B.1.525), identified in Nigeria as of December 2020
It is one of the variants “downgraded” by the WHO. There is insufficient data to define whether it is more transmissible or more pathogenic (and lethal) , but Eta too has shown a certain “immune leak”.
Theta (P.3), identified in the Philippines in January 2021
It is one of the variants “downgraded” by the WHO. It has an increased transmissibility (while the impact on disease severity is unknown) and shows a capacity for partial “immune escape”.
Iota (B.1.526), identified in the United States in December 2020
Another variant “Downgraded” by the WHO. It is not clear whether it has increased transmissibility or severity of the disease, while showing a capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection.
Kappa (B.1.617.1), identified in India in December 2020
It is one of the variants “downgraded” by the WHO. Has a’increased transmissibility (while the impact on the severity of the disease is unknown) and shows a capacity for partial “immune escape”.
Lambda (C.37), identified in Peru in December 2020
It is classified as “Variant of interest” (You). It is not clear whether it has increased transmissibility or severity of the disease, while showing a capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection.
Mu (B.1.621), identified in Colombia in January 2021
It is classified as an “interest variant” (Voi). It has an increased transmissibility (while the impact on disease severity is unknown) and shows a capacity for partial “immune escape”.
The letters Nu and Xi were “skipped” by the WHO for different reasons (“Nu” would sound too similar to English new, while ‘Xi’ is an extremely common surname, especially in China).
Omicron (B.1.1.529), identified in Botswana and South Africa in November 2021
Present a number high number of S gene mutations compared to the original virus (Wuhan strain). From empirical observation it seems to enjoy a very high transmissibility and shows one capacity for partial “immune escape” compared to the protection induced by vaccines or a previous infection. However, it is the first variant that has been linked to less severe forms of diseases.
Many other variants (which have not been assigned a name, but only an acronym) have been registered by the WHO and some are still under observation, but without for the moment arousing concern. Among these is also the “sister” of Omicron (lineage BA.2). In Italy, according to the latest survey by the Higher Institute of Health (data of January 17), the Omicron variant is 95.8% predominant, while Delta represents 4.2% of the sample examined. The first cases of BA.2 from our country also appeared on the Gisaid platform (worldwide database of Sars-CoV-2 sequences).
January 29, 2022 (change January 29, 2022 | 11:09 am)
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