Covid variants, from Alfa to Omicron (hopefully the last): the list and history – Corriere.it

If we were to complete the Greek alphabet, you’d miss 9, even omega, but the hope – now whispered – is that we can stop at Omicron, or at worst for Pi. Tedros Adhanom GhebreyesusThe Director-General of the World Health Organization (WHO), hinted at this There is no need to be overly optimistic: conditions remain ideal for further development Variants of the coronavirus
And it’s dangerous to assume we’re in the final stage, he said, but it could be The acute phase of the pandemic ends this year If some key objectives are achieved. for example Vaccinate 70% of every country’s population by mid-2022, focusing on people at high risk of severe COVID-19, and increasing levels of testing and sequencing. Just to say, only 11% of the population in Africa is fully vaccinated.

evasion of immunity

Two years into the pandemic have taught us that the longer the virus is allowed to “run”, the greater the risk of new variants forming, potentially at least partially evading the immunity conferred by previous vaccines or infections. When a virus replicates it can modify itself, causing mutations to appear in its genome: this is especially true for those with RNA (such as coronaviruses). If the new version begins to spread, for example to increase transmissibility or the ability to circumvent previously acquired immunity, a new one is identified variable “worry” (You are, alternative to anxiety). The SARS-CoV-2 virus, which is constantly monitored around the world, has produced hundreds of variants of its own, but most mutations have little effect on the course of the pandemic. Here are the variables recorded and those that raised the greatest alarm.

Alpha (B.1.1.7), set in the United Kingdom in September 2020

It has a higher transmissibility than the original strain (Wuhan strain), which leads to a higher number of infections and therefore an increase in severe cases. The Alfa variant has been ‘downgraded’ by the World Health Organization (so it is no longer a ‘kind of concern’), because Its circulation decreased significantly with the emergence and spread of the delta. The properties of alpha are to increase the transmissibility and severity of the disease, while the effect 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 September 2020
Although it does not appear to be characterized by greater transmissibility, this variant could lead to a partial effect of immune escape Against vaccine-induced antibodies and some monoclonal antibodies. Beta is still classified as a ‘variant of concern’: it has a higher transmissibility than alpha and causes more serious illness..

Gamma (P.1), set in Brazil in December 2020

Studies have shown a potential for increased transmissibility and a potential risk of re-infection. Gamma is still classified as a “variant of concern”: it confers more severe forms of Covid than previous variants and the ability for partial “immune escape” compared to protection from vaccines or a previous infection.

Delta (B.1.617), identified in India December 2020

Marked by Transmissibility 40 to 60% higher than the alpha variant It is associated with a relatively higher risk of infection in unvaccinated or partially vaccinated individuals. Delta is still classified as a “variable of concern”: it has increased disease transmissibility, severity, and partial “immune escape” compared to protection from vaccines or a previous infection.

Epsilon (B.1.427 / B.1.429), specified in the US as of September 2020

It is one of the variables who “lowered” (such as alpha), because Its spread is very limited. It is not clear whether it increased transmissibility or caused more severe disease than previous variants, while it has been shown to partially escape immune protection.

Zeta (p. 2), set in Brazil in January 2021

It is one of the variables that the World Health Organization has “downgraded”. It is unclear whether it increased transmissibility or caused more severe symptoms, but certainly, like the previous symptoms, Shows ability for partial ‘immune escape’ Compared to protection from vaccinations or a previous infection.

Age limit (B 1.525) in Nigeria as of December 2020

It is one of the variables that the World Health Organization has “downgraded”. There is not enough data to determine whether it is more transmissible or more pathogenic (and fatal) , but ETA also showed a certain ‘immune leakage’.

Theta (p. 3), set in the Philippines in January 2021

It is one of the variables that the World Health Organization has “downgraded”. It has an increased portability (while The effect on disease severity is unknown) and shows the ability for partial “immune escape”.

Iota (B.1.526), ​​identified in the US December 2020

another type WHO ‘downgraded’. It is not clear whether it increased disease transmissibility or severity, while showing the ability for partial ‘immune escape’ compared to protection from vaccines or a previous infection.

Kappa (B.1.617.1), set in India December 2020
It is one of the variables that the World Health Organization has “downgraded”. he have “Increase portability (While the effect on disease severity is unknown) It shows the ability for partial ‘immune escape’.

Lambda (C.37), identified in Peru in December 2020

classified as “variable of interest” (You are). It is not clear whether it increased disease transmissibility or severity, while showing the ability for partial ‘immune escape’ compared to protection from vaccines or a previous infection.

Mu (B.1.621), identified in Colombia Jan 2021

It is classified as a “variable of interest” (Voi). It has an increased portability (while The effect on disease severity is unknown) and shows the ability for partial “immune escape”.

The letters Nu and Xi have been “skipped” by the World Health Organization for various reasons (“Nu” might sound very similar to English the new, while “Xi” is a very common surname, especially in China).

Omicron (B.1.1.529), set in Botswana and South Africa in November 2021

Show a number High number of S gene mutations compared to the original virus (Wuhan dynasty). From experimental observation it appears to have a very high transmittance and shows one The ability to partial ‘immune escape’ Compared to protection from vaccinations or a previous infection. However, it is the first option that has been linked Less severe forms of disease.

Several other variants (for which no name is assigned, but only an acronym) have been registered by the World Health Organization and some are still being monitored, but without causing concern at the moment. Among them too “Sister” Omicron (BA.2 pedigree). In Italy, according to the latest survey conducted by the Higher Institute of Health (data January 17), Omicron variant is 95.8% predominantWhile delta represents 4.2% of the sample examined. The first cases of BA.2 from our country also appeared on the Gisaid platform (Global Database of Sars-CoV-2 Sequences).