How many Covid-19 variants have been there besides Omicron? what are their differences?

Viruses are constantly mutating as they reproduce inside a host trying to become more efficient at spreading to new ones while evading immune system defenses. The original strain of covid-19 has gone through a similar process.

Not all of these new iterations are as effective as the previous, but some have developed to replace the original strain of the novel virus identified in December 2019 as “SARS-CoV-2”, or better known as covid-19. Since it was first discovered in Wuhan, China, several variants of the virus have been identified around the globe but only 13 have received a simplified name to aid health officials in explaining the new variant to the public, and how it is different from prior versions.

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Variants classified according to transmissibility and severity of disease

Countless variants have developed over the nearly two years since covid-19 was first discovered in a cluster of patients in China who were experiencing fever and a shortness of breath. Eventually, those cases were traced back to the Huanan Seafood Wholesale Market in Wuhan. Despite draconian efforts to contain the novel virus it was already globetrotting, appearing in various nations across the world.

Without a vaccine to slow its march, the novel virus took a devastating toll on populations and new iterations began to appear. The World Health Organization (WHO) was monitoring the new strains as they were identified, classifying the variants whose mutations necessitated greater scrutiny based on possible higher transmissibility or causing more severe disease.

The WHO and the Centers for Disease Control and Prevention (CDC) separate the different variants that need to be monitored into different levels of perceived risk. Those that need to be monitored, variants of concern and interest and those of high consequence. Fortunately, none of the new strains have been classified in the last group, but the WHO has placed five variants into the Variant of Concern (VOC) grouping, among them the latest covid-19 variant Omicron. Of the other four, Alpha, Beta Gamma and Delta, only the last is listed as such in the US by the CDC.

The WHO currently has two variants, Lambda and Mu, on its list of “interest”. The other six variants that got Greek alphabet names have been lowered to “Variants Under Monitoring” or removed altogether. Currently the CDC is monitoring ten variants with none in the “of interest” classification as Delta has been the primary variant causing infections across the US since it began outcompeting all other strains.

Only some variants are given names

The WHO has given 13 of the 33 variants that it has tracked at some point during the pandemic a name based on the Greek alphabet. Prior to May 2021, new variants were referred to by their scientific name, a letter and a number or series of numbers.

These codes convey important scientific information for researchers working to tackle the pandemic and are still used. However, they were confusing to the public at large, difficult to recall and say, leading people referring to them by the places they were first detected, which was found to be stigmatizing and discriminatory.

Thus the WHO set up a labeling system based on the Greek alphabet to make the variants of interest and concern easier to say and simplify diffusion of information about them to the public. Those that have been or are still being monitored but haven’t risen to “interest or concern” are only referred to by their scientific name.

How are the variants different?

Fortunately, none of the variants has shown a significant ability to bypass the immunity given by the three vaccines available in the US produced by Pfizer, Moderna and Johnson and Johnson. Most importantly those who are vaccinated have been able to avoid more serious illness and thus hospitalization even against the Delta variant which has proven to be the most transmissible in the US so far displacing all the other variants.

Researchers are still studying if this will be true for the Omicron variant given the number of mutations it has. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and the White House chief medical adviser, speaking on ABC’s This Week said "the mutation would strongly suggest that it would be more transmissible and that it might evade ... perhaps even antibodies that are induced by vaccine." But he and other health experts have caution that people should not panic.

It is too early to know for sure how effect the available vaccines will be against Omicron but “being vaccinated is the best situation to be in until we have further information," former acting director of the CDC Dr Richard Besser told Lestor Holt on NBC Nightly News. A recommendation seconded by Dr. Fauci and many other health experts.