Coronavirus: All about different COVID-19 variants and vaccines effective against them

With passing day, we are seeing the emergence of newer virus variants spreading across the world. While the variants originate from the same strain, all have different features which make them less or more severe in comparison.

Dr Mala Kaneria, Consultant, Department of Infectious Diseases, Jaslok Hospital, Mumbai helps settle your doubts.

How many variants of SARSCoV2 are there in India?
Viruses by nature are known to mutate and these mutations are important for their survival and propagation. The original Wuhan strain of SARSCOV2 has mutated multiple times since its emergence.

Many variants have gained the attention of health authorities, such as Alpha, Beta, Gamma, Delta, Delta Plus, Lambda, Eta and lota. B.11.318 and B.1.617.3 are some other variants.

What is the difference between the variants?

The Delta variant (B.1.617.2), which was first found in India, was a variant of Interest (VoI) in April 2021 and subsequently became a Variant of Concern (VoC) in May 2021, when it led to the lethal second COVID-19 wave, which devastated the country. Delta has emerged as a threat across the world as most of the present Covid-19 cases in the world are that of Delta variant. The Delta Variant is not only severalfold more transmissible and causes more severe symptoms but is also 8 times less effective against vaccines as compared to the original strain of COVID-19. This mutant is now found in most countries and is responsible for the surge of cases in the UK and Israel.
The Delta Plus variant (AY.1), a derivative of the Delta wave, contains the K417N spike protein mutation, which was first seen in the Beta variant (South African). This is a variant of concern (VoC) since it was observed that vaccines were not very effective against the related Beta strain.
The Kappa variant (B.1.617.1), also related to the Delta variant, has two mutations (L452R and E484Q), out of which L452R is an escape mutation which gives immune protection to the virus. Two cases of Kappa have been reported from Uttar Pradesh very recently.
Lambda, the seventh VoI, containing the mutations L452Q and F490S, has originated from Peru, the country with the highest mortality. Both Kappa and Lambda are currently labelled as Variants of Interest (VoI) by the WHO.

Which one is more lethal or dangerous?
Delta is the most lethal as it was responsible for the huge number of cases and an increase in deaths during the second wave in India. Delta Plus, being a derivative of Delta also has attributes of increased transmissibility, ability to bind more strongly to receptors on lung cells, and the potential to evade an antibody response, though there is no hard data on the lethality. However, some scientists believe that the K417N may actually weaken the Delta Plus strain and it may not be as lethal as the Delta strain. Not much is known about the lethality of Kappa and Lambda, which is currently not found in India.

Why is Delta Plus termed ad VoC while Lambda is called VoI ?
If a variant is found to be more transmissible, more resistant to antibodies, or to cause more severe disease, it is designated a VOC. Delta and possibly Delta Plus have exhibited these traits and hence are termed VoCs. However, there are no cases of Lambda in India so far and its lethality is not known, therefore it is just a VoI presently.

Are these new variants vaccine-resistant?
Existing vaccines do work against the original Delta variant but are less effective in those who do not mount a robust immune response. The Delta Plus variant due to its escape mutation K417N, may dodge vaccines and antibodies better than Delta. The leading vaccines however are thought to offer protection against severe disease and hospitalization against most strains.

Which vaccines are more effective?
The AstraZeneca and n Pfizer vaccines remain broadly effective against Delta and Kappa variants. There is no evidence of widespread escape suggesting that the current generation of vaccines will provide protection against the B.1.617 lineage. However, the concentration of neutralising antibodies in the blood may reduce, which may lead to some breakthrough infections. Recent data shows that a third booster dose of Pfizer would be more effective against the Delta strain, as antibodies to this variant decline faster.