SARS-CoV-2 Variants

The vocabulary of the novel coronavirus variants.

Just like the flu virus, the novel coronavirus or the SARS-CoV-2 also changes over time. This change happens through mutation, which refers to changes in the genetic sequence of the SARS-CoV-2 in comparison to originally identified variants. For SARS-CoV-2, the baselines or the originals are the Wuhan-Hu1 and USA-WA1.

Since the first sequencing till present, the genetic sequence of the SARS-CoV-2 has changed in different ways. These changes or variants are tracked worldwide so that scientists can better understand the properties of the variants and their impact on the response to the pandemic. The group of scientists in the US at the SARS-CoV-2 Interagency Group (SIG) continuously updates their knowledge about the new variants and how they might impact action to control the pandemic. The goal of the SIG is to quickly understand how the new variants could impact the efforts to diagnose and treat Covid-19. In addition, the variants can also have an impact on the effectiveness of the vaccines.

We have recently heard a lot about the “double” mutant circulating in India. What exactly does that mean? My attempt in this story is to help myself and others understand the terminology used to discuss the variants of SARS-CoV-2 and how they impact the various responses to control and hopefully end the pandemic.

Image by the author. Image description: classification of the SARS-CoV-2 variants on an inverted pyramid.

Variant Categories

The variants are grouped into three categories as follows:

1. Variants of Interest (VOI) — This variant’s genetic makeup changes its binding behavior at the cell receptor sites in the body. With this change, the antibodies may not be as effective even in a vaccinated person. These variants are monitored because they can lead to an increase in positive cases.
2. Variants of Concern (VOC) — This variant can spread faster between people and result in more severe symptoms. Previously effective treatments may not work, and diagnostic tests might fail to detect the VOCs.
3. Variants of High Consequence (VOHC) — This type of variant has the same characteristics as the VOCs. In addition, there is unquestionable proof that treatment and other efforts to treat and contain the disease are ineffective. Vaccine efficacy against…