Introduction to Coronavirus Variants: Omicron, Delta, Alpha, and others

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What causes covid-19?

SARS-CoV-2, the virus that causes Coronavirus, is continually mutating, and very quickly spreads. There have been several notable varieties since the pandemic’s start, including Alpha, Beta, Delta, and Omicron.

Although new variations of viruses are a normal part of their evolution, keeping track of each one as it emerges is crucial for ensuring that the world is prepared. This is particularly true if a new variety of the virus is more aggressive, extremely contagious, immune to vaccination, capable of producing more severe disease, or all of the above, in comparison to the original strain.

WHO classification of the Coronavirus variants

The Greek alphabet is used by the World Health Organization (WHO) to designate novel coronavirus varieties, beginning with the Alpha variety, which first appeared in 2020.

The list and details of some of the most popular mutations are provided below.

Variants of Coronavirus

1) Alpha variant (Variant of concern)                   

Alpha (B.1.1.7) was the first of the highly publicized variants. Alpha first appeared in Great Britain in November 2020 and infections surged in December of that year. It soon surfaced around the world and became the dominant variant in the U.S., where the CDC classified it as a variant of concern. Then, Alpha faded away with the rise of the more aggressive Delta variant.

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Does it spread very quickly? 

The spike protein in Alpha was thought to have several alterations that increased its infectiousness. According to estimates, the B.1.1.7 lineage was 30 to 50% more contagious than the original SARS-CoV-2 strain. According to a CDC report published in June, Alpha made up 66% of cases in the United States in mid-April 2021, before Delta became predominate.

Gravity of variant

According to studies, the B.1.1.7 lineage was more deadly than the original virus and was more likely to send sick persons to the hospital.

Vaccines’ effectiveness against it

In the cases of Alpha, Pfizer, Moderna, and Johnson & Johnson all claimed that their vaccines were successful in averting serious illness and hospitalization.

2) Delta variants

When the coronavirus Delta (B.1.617.2) was initially discovered in India in late 2020, it quickly spread over the globe and took over as the dominant strain—until Omicron replaced it in mid-December.

Does it spread easily?

In Connecticut, it was estimated that the Delta variant was 80 to 90 percent more communicable than the Alpha version, leading to more than twice as many infections as the earlier variants. After a steady drop in COVID-19 instances and hospitalizations in the U.S. from June 2021 to June 2022, the arrival of Delta was accompanied by a sharp reversal of that trend. Even the states with the highest vaccination rates experienced spikes in the fall of 2021, prompting specialists to advise patients to obtain their booster vaccines.


People who weren’t immunized were more susceptible to Delta than other types of the disease. The CDC noted early research from Scotland and Canada that found unvaccinated people had a higher risk of hospitalization from Delta. 

Are vaccines helpful?

In the US, all three immunizations were regarded as being quite effective against fatal cases of Delta, including severe sickness, hospitalization, and death. No vaccine is 100% effective, and in some completely immunized individuals, Delta led to breakthrough infections. Infected vaccine recipients might also transmit the virus to others; however, they were probably only contagious for a shorter period of time.

3) Beta variants

By the end of 2020, this variety, known as B.1.351, had been discovered in South Africa and afterward it was detected in other countries. Due to its numerous mutations and propensity to elude antibodies, experts had expressed worry. 

Its ability to propagate

According to the CDC, Beta was around 50% more contagious than the primary coronavirus strain.


The likelihood that Beta would result in hospitalization and mortality may have been higher than that of other variations, according to the available research.

Response to vaccines

Clinical testing revealed the AstraZeneca-Oxford vaccine did not offer robust protection against mild and moderate sickness from the Beta strain, therefore early in 2021, South Africa discontinued distributing it (the vaccine is not offered in the U.S.). Johnson & Johnson, Moderna, and Pfizer-BioNTechalloffered modest immunity against the Beta variant.

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4) Omicron and its variations                    

Regarding Omicron and the other Omicron sub-variants that have surfaced, there is still a great deal to learn. After the initial Omicron strain (BA.1) was discovered in South Africa and Botswana in late November 2021, it was learned that this particular variant spread faster than the previous mutation but is less lethal. By December, Omicron was responsible for a sharp increase in the number of daily cases in the US to over a million. One of those sub-variants, BA.5, represented more than 50% of instances in the United States by the beginning of July 2022, making it the predominant variant in the country. A related variety, BA.4, which accounts for around 17% of cases, was also on the rise.

Does it spread easily?

The BA.5 and BA.4 forms seem to be better than other sub-variants at escaping protection offered by vaccines and prior illness, and Omicron’s sub-variants are thought to be particularly effective purveyors of the disease (although doctors say the vaccines still provide important protection against severe disease and death)

Omicron’s initial variant was more contagious than Delta. One explanation was that the virus’s spike protein, which connects to human cells, had more than 30 alterations, many of which are thought to increase the likelihood of infection.


The BA.5 and BA.4 sub-variants can lead to more severe diseases than their ancestors, however, to get into the gravity of the situation additional research is still needed. According to the CDC, data indicate that the initial Omicron strain was, on average, less severe than earlier variations.

Effect of vaccines on it

According to the CDC, being vaccinated, or have been through a prior infection, and receiving a booster injection are your best lines of defense against Omicron, even though breakthrough infections in vaccinated individuals are likely.

Other variants

other variants of coronavirus

Omicron and its sub-variants are currently the focus of the CDC’s attention as variants to watch in the US. B.1.1.529, BA.1, BA.1.1, BA.2, BA.3, BA.4, and BA.5 are included in this. The designation is given to variations that exhibit enhanced transmissibility, the potential to cause more severe disease, the potential to avoid diagnostic identification, and/or the potential to be resistant to antibodies from prior infections or vaccinations.

The organization is nonetheless keeping an eye out for additional variations that are either no longer being found in the United States or are spreading so slowly that they don’t pose a big threat. They also include the 1.617.3 version, Gamma, Epsilon, Eta, Iota, Kappa, Mu, and Zeta in addition to Alpha Beta and Delta. One of the worries raised by experts is that the lack of universal access to immunizations may result in spikes in COVID-19 cases, increasing the likelihood that alarming variants will keep surfacing.

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