Explained: The highly transmissible SARS-CoV-2 variants

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What are the SARS-CoV-2 variants?

The SARS-CoV-2 virus, like other viruses, is constantly changing. Once inside the human body, the virus starts making copies of its genetic code (RNA). Occasionally, the virus mutates when it fails to produce the exact copies of its genetic material. When the virus mutates significantly, new SARS-CoV-2 variants emerge.

How many SARS-CoV-2 variants are in circulation globally?

It is difficult to estimate the number of variants in circulation across the world. In most cases, new variants emerge and disappear rather quickly. However, some of the variants persist and are tracked by scientists through genomic surveillance. When a variant begins to pose a risk to public health, it is characterized as a Variant of Concern (VoC).

SARS-CoV-2 Variants of Concern

A SARS-CoV-2 variant is designated as a variant of concern (VOC) when there is evidence of an increase in transmissibility, risk of severe disease or death, a significant reduction in neutralization by antibodies, or reduced effectiveness of treatments or vaccines. Currently, there are four VOCs: Alpha, Beta, Gamma, and Delta.

Alpha variant

First identified in the UK, the Alpha variant is considered to be 40%-80% more transmissible than the original strain. According to scientists, the variant may be associated with a higher risk of hospitalization and death. Some of the notable mutations in the variant include N501Y, P681H, and E484K.

Beta variant

The Beta variant was first detected in South Africa in October 2020. It is estimated to be at least 50% more transmissible than the previous circulating variants. The variant is suspected to reduce the effectiveness of COVID-19 vaccines. K417N, E484K, and N501Y are three key mutations in the Beta variant.

Gamma variant

The Gamma variant is believed to have emerged in Brazil in November 2020. Evidence suggests that the variant lowers the effectiveness of some monoclonal antibody medications and the antibodies generated by a previous infection or vaccination. N501Y, E484K, and K417T are three notable mutations in the Gamma variant.

Delta variant

The Delta variant was first identified in India in October 2020. Scientists say that the Delta variant is 40%-60% more transmissible than the Alpha variant. According to Mike Ryan, Executive Director, WHO's Health Emergencies Programme, "The delta variant is the most able and fastest and fittest of those viruses.”

What makes the Delta more transmissible than other variants?

High viral load and short incubation period are believed to be two major reasons behind the Delta variant’s high transmissibility. The variant triggers the accumulation of a massive amount of virus in the respiratory tract that causes infected individuals to spread the virus to more people earlier after they become infected.

Is the Delta variant more deadly than other SARS-CoV-2 variants?

Researchers are still trying to determine if the Delta variant is more deadly than the rest of the VOCs. However, as more data become available, the Delta variant will likely prove to be associated with the higher odds of hospitalization and death. The risk is especially high for unvaccinated people.

Are vaccines effective against the Delta variant?

Available scientific evidence suggests that the variant may adversely affect the effectiveness of the vaccines. However, the vaccines are likely to reduce the risk of hospitalization and mortality. According to a study, Pfizer and AstraZeneca vaccines prevent the risk of hospitalization from Delta variant by 96% and 92% respectively.

How to protect yourself against the Delta variant?

One simple way to protect yourself against the Delta variant is to get vaccinated as soon as possible. Although the variant is associated with reduced neutralizing antibodies, the vaccine will still offer protection against severe disease and death. It is also important to follow COVID-appropriate behavior unless advised otherwise.

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