New Delhi: Yet another Covid variant has reared its head, creating panic worldwide over a fourth wave of infections and scurrying nations to intensify screening at airports.


The XE Covid variant, which is said to be highly transmissible, is being blamed for a surge in cases in China, Hong Kong, South Korea, UK and Germany. In India, two states -- Maharashtra and Gujarat -- claimed to have detected a case of XE Covid variant each.


In fact, XE is a combination or recombinant of Omicron sub-variants —BA.1 and BA.2.


Even though experts have said there is no need to panic, XE is among the several coronavirus variants have been identified since December 2020. 


Since the beginning of the pandemic, we have seen a number of prominent variants, including Alpha, Beta, Delta, and Omicron. 


What Is A Covid Variant?


As viruses spread, they produce more copies on their own. During this process, they mutate, causing the new copies of the virus to not be exact replica of the original or parent virus. A copy that is different from the original virus is called a variant.


SARS-CoV-2, the virus that causes Covid-19, has gone through this type of mutation many times in the past two years.  


The World Health Organization (WHO) names new coronavirus variants using the letters of the Greek alphabet, starting with the Alpha variant, which emerged in 2020.


READ | XE Variant Another Version Of Omicron, Precautions Still Needed: Health Minister Mandaviya


How Many Covid Variants Have Been Detected So Far?


So far, 10 major Covid-19 variants have been detected by the WHO and two -- Delta (B.1.617.2) and  Omicron (B.1.1.529) -- have been classified as variants of concern.


The 10 variants are B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.427 and B.1.429 (Epsilon), B.1.525 (Eta), B.1.526 (Iota), B.1.617.1 (Kappa), B.1.617.3, P.2 (Zeta), and B.1.621 and B.1.621.1 (Mu).


Alpha Covid Variant


Alpha (B.1.1.7) was the first major Covid-19 variant detected in the UK in November 2020, leading to a surge in cases across the world. It soon became the dominant variant in most nations, including India and the US.


According to the WHO, the Alpha variant was said to be 30-50 per cent more contagious than the original SARS-CoV-2 strain. It was designated a variant of concern in December 2020.


In terms of severity, people infected with the Alpha variant required hospitalisation, with experts saying that the variant was deadlier than the original virus.


Beta Covid Variant


First identified in South Africa in early 2020, Beta or B.1.351 was classified as variant concern due to its several mutations and its potential to evade antibodies. 


According to the US CDC, the Beta variant is about 50 per cent more contagious than the original coronavirus strain and is more likely to lead to hospitalisation and death.


Gamma Covid Variant


Gamma was designated a variant of concern in January, 2021, after being first detected in Brazil. While not deadly like Alpha and Beta, the Gamma variant is said to be 1.7 to 2.4 times more transmissible than non-variants of concern.


Delta Covid Variant


Responsible for the deadly second wave of Covid infections across the world, the Delta or B.1.617.2 variant was first identified in India in early 2021. By March 2021, it became the predominant version of the coronavirus in several countries, overwhelming hospitals and resulting in massive deaths.


The variant spreads more quickly and is more than twice as contagious as previous variants. Studies suggest Delta doubles the risk of hospitalisation compared with Alpha and vaccines are slightly less effective against preventing infection.


Omicron Covid Variant


Omicron spread across the world at a faster rate than previous variants after it was detected in November 2021 in South Africa's Gauteng province. Even though Omicron causes less severe disease, it has a large number of spike protein mutations and is highly infectious.  


Omicron leads to an increased risk of reinfection compared to other variants of concern. It has few major offshoots, including BA.1, BA.2 (now globally dominant) and BA.3.



Recently, two more sub-variants -- BA.4 and BA.5 -- discovered in South Africa are being monitored by the WHO because of their "additional mutations", Reuters reported.


The UK's Health Security Agency said BA.4 was found in South Africa, Denmark, Botswana, Scotland and England from January 10 to March 30.


BA.5 has been detected in South Africa and Botswana. The BA.4 and BA.5 cases reported in South Africa displayed mild symptoms. However, all those who contracted the variants were fully vaccinated.