First, let’s discuss what variants are and how a virus is able to spread into new types of variants. According to CDC, “As the virus spreads, it has new opportunities to change and may become more difficult to stop. These changes can be monitored by comparing differences in physical traits (such as resistance to treatment) or changes in genetic code (mutations) from one variant to another.” New strains of the virus tend to have different characteristics; thus, they have different impacts on the population as well.
There are 4 different classes of Covid-19 variants; variant being monitored (VBM), variant of interest (VOI), variant of concern (VOC), and variant of high consequence (VOHC). There are currently 11 variants (Table 1) being monitored in the United States, and one variant of interest.
Our current variant of interest as of April 26, 2022 is the Omicron variant. This specific strain of the Covid-19 virus seems to potentially have a higher transmission rate than previous variants.
| WHO Label | Pango Lineage | Date of Designation | ||
| Alpha | B.1.1.7 and Q lineages | VOC: December 29, 2020 | VBM: September 21, 2021 | |
| Beta | B.1.351 and descendent lineages | VOC: December 29, 2020 | VBM: September 21, 2021 | |
| Gamma | P.1and descendent lineages | VOC: December 29, 2020 | VBM: September 21, 2021 | |
| Delta | B.1.617.2 and AY lineages | VOC: June 15, 2021 | VBM: April 14, 2022 | |
| Epsilon | B.1.427B.1.429 | VOC: March 19, 2021 | VOI: February 26, 2021VOI: June 29, 2021 | VBM: September 21, 2021 |
| Eta | B.1.525 | VOI: February 26, 2021 | VBM: September 21, 2021 | |
| Iota | B.1.526 | VOI: February 26, 2021 | VBM: September 21, 2021 | |
| Kappa | B.1.617.1 | VOI: May 7, 2021 | VBM: September 21, 2021 | |
| N/A | B.1.617.3 | VOI: May 7, 2021 | VBM: September 21, 2021 | |
| Zeta | P.2 | VOI: February 26, 2021 | VBM: September 21, 2021 | |
| Mu | B.1.621, B.1.621.1 | VBM: September 21, 2021 |
Table 1. Captured from the CDC website.
While there are Covid-19 variants that fit into the categories of variant being monitored (VBM) and variant of concern (VOC), there are currently no variants of interest (VOI) nor are there any variants of high consequence (VOHC) in the United States.
What is a variant being monitored?
VBM are variants which no longer pose a significant threat to the public. CDC states that these variants are those where “data indicates there is a potential or clear impact on approved or authorized medical countermeasures or that have been associated with more severe disease or increased transmission but are no longer detected, or are circulating at very low levels, in the United States.” The variants being monitored are often previously variants of concern (VOC) that demonstrated a significant decline in their proportion in the United States, and are continuing to be monitored to this day.
What is a variant of concern?
The CDC classifies a variant of concern (VOC) as a strain that shows higher levels of transmissibility, tends to be more severe, demonstrates great decrease in neutralization by antibodies, and decline in treatment or vaccine efficacy. These tend to be newer strains of the virus that have a larger impact on the public.
What are some measurements taken to control VOC?
In order to contain the spread of these variants, a few of the following public health actions are taken. WHO is notified of the VOC, in addition to being disclosed to the CDC. Local and regional efforts, more testing, increased research towards analyzing the efficacy of the vaccines and treatments against the VOC. Further action is taken regarding new vaccine and treatment modifications.
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Visit CDC.gov to learn about the different classes of Covid-19 variants and their severity.
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