Viruses such as SARS-CoV-2 continuously evolve as changes in the genetic code occur. These changes are caused by genetic mutations or viral recombination. When a viral genetic code has one or more mutations that differentiate it from a previously known version of the virus, it is a variant. Variants of the SARS-CoV-2 virus may be more transmissible and can lead to more severe disease, posing a significant risk to public health. Being fully vaccinated is the best protection against variants.
Variants of a virus are common and therefore expected. The CDC and other national and international public health organizations are tracking multiple COVID-19 variants and subvariants occurring around the world. The CDC’s the National SARS-CoV-2 Strain Surveillance (NS3) program has worked to increase the number of viruses being tracked and studied.
The CDC has different classifications for SARS-CoV-2 variants:
- Variants of Interest (VOI),
- Variants of Concern (VOC),
- Variants Being Monitored (VBM) and
- Variants of High Consequence (VOHC).
You can learn more about how these categories are defined here. You can view the national proportion of variants and subvariants on the CDC COVID-19 Data Tracker here. In South Carolina, DHEC monitors the same variants as the CDC, which are shown in the dashboard below.
Whole-genome sequencing (WGS) is the process of determining an organism’s entire genetic sequence at a point in time. Recent advances in WGS techniques, currently named next-generation sequencing (NGS), allows for cheaper, faster, and more accurate sequencing for use in various applications such as determining infectious disease outbreaks. Sequences obtained from NGS are analyzed for mutations and further classified into variants.
DHEC’s Public Health Laboratory (PHL) staff are trained to perform WGS on SARS-CoV-2. Since June 2020, DHEC's PHL has been conducting sequencing on randomly selected samples as part of national efforts to identify variants. In addition, DHEC receives COVID-19 WGS results from labs across the state and from national reference labs. Together, this provides a picture of variant activity in South Carolina.
DHEC’s COVID-19 Variant Dashboard is updated every Tuesday and contains information relevant to SARS-CoV-2 variant proportions for the most common variants in SC. The dashboard contains data from all laboratories who perform testing for COVID variants and have submitted results to DHEC. Data can be filtered by timeframe (one-week periods), and if a specific timeframe is selected in the chart, the data will change in the table to reflect the selected timeframe.