DNA Explainer: How is Gamma different from Delta? Why is it 'Variant of Concern'?

It was the year 2019 when the world first heard of a pneumonia outbreak in China's Wuhan province. China became alert and the streets of Wuhan gave a deserted look. A lockdown was announced in the entire province and people were not allowed to go out of their homes.

Any person with fever, cough and cold were picked up from their houses and admitted to hospitals by people covered in PPE kits. But even before the world could actually understand the outbreak and its intensity there was not much time left to take any special precautions.

The world had come under the grip of a new pandemic, unheard of till now. World Health Organisation named it the COVID-19 pandemic or the coronavirus outbreak which claimed countless lives within a span of two years.

At the outset, the virus spread through droplets of saliva, cough particles or nasal discharge from an infected person. Within the passage of a year, there was an emergence of changing COVID-19 variants with the virus continuously mutating itself. With these changes, the new variants became more powerful and contagious than the original Wuhan virus.

The changes in the variants occur when there is a mutation of the genes of the virus.

The World Health Organisation has classified each emerging variant as either a Variant of Concern (VOC) or a Variant of Interest (VOI). The Alpha, Beta, Gamma, and Delta variants fall under 'Variants of Concern'. Whereas Eta, Iota, Kappa, and Lambda fall under 'Variants of Interest'.

Variants of Concern

Delta (B.1.617.2) first identified in India, currently accounts for 99% of new COVID cases in the UK.

Alpha (B.1.1.7), first identified in the UK but which has spread to more than 50 countries and appears to be mutating again

Beta (B.1.351), first identified in South Africa but which has been detected in at least 20 other countries, including the UK

Gamma (P.1), first identified in Brazil but has spread to more than 10 other countries, including the UK.

What is a Variant of Concern?

According to the World Health Organisation, a variant of concern translates to a rise in transmissibility, an increase in fatality, and a significant decrease in the effectiveness of vaccines, therapy, and other health measures.

Gamma Variant

The Gamma variant of the novel coronavirus, first found in Brazil, has been detected in small quantities in Russia.

Russia faces a surge in coronavirus cases that authorities have blamed mostly on the Delta variant and the slow rate of vaccinations.

Delta and Gamma variants are categorised as 'causing concern' because they spread more easily and can reduce the effectiveness of antibodies.

The first cases of the Gamma variant were detected in the US in January 2021 in a group of travellers from Brazil.

According to the Global Virus Network (GVN), P.1 or the Gamma variant has shown pronounced transmissibility. 

Its mutations N501Y, K417N and E484K in the 'receptor building domain of spike protein', tend to amplify its affinity to human receptors.

This variant tends to escape from the immune responses of the body. With each mutation, the virus becomes more contagious than its previous strains.

Difference between Delta and Gamma variants

When Delta first appeared in the UK at the start of April, it rapidly overcame Alpha and now accounts for around 90% of new cases.

Gamma, on the other hand, is not such a rapid spreader, but it does slightly knock back the effectiveness of vaccines.

Delta and Gamma are fast overtaking Alpha in the US, which has already fallen from dominance from 70% of cases in April to around 35%.

Delta and Gamma collectively made up around 30% of all cases in the US as of June 9 with Delta making up around 14% and Gamma 16%.

Researchers looked at how the two variants Delta and Gamma were spreading in various counties.

They found, the growth curve for Delta, which is more transmissible but against which vaccines are highly effective, shows faster growth in counties with lower vaccination rates.

In contrast, Gamma which is less transmissible but against which vaccines have somewhat less efficacy has a higher prevalence in counties with higher vaccination rates.