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#16,371
Although it was pretty much a foregone conclusion, yesterday the United States officially classified the Omicron variant as a VOC (Variant of Concern), with the following announcement on the CDC's Coronavirus website.
What You Need to Know about VariantsUpdated Nov. 30, 2021Languages
Omicron VariantOn Tuesday, November 30, 2021, the U.S. government SARS-CoV-2 Interagency Group made the decision to classify the Omicron variant as a Variant of Concern (VOC). This decision is based on multiple factors, including the detection of Omicron cases in multiple countries, transmission and displacement of Delta in South Africa, and mutations in the virus that could indicate a reduction in the effectiveness of COVID-19 vaccines and certain monoclonal antibody treatments. No cases of this variant have been identified in the U.S. to date. CDC is following the details of this new variant.
While the WHO declared Omicron a VOC on Friday, each country has its own evaluation system, and indeed, their own classification system, for variants. In the United States there are currently 4 categories of COVID variants (VBMs, VOIs, VOCs, and VOHC), with VOHC representing the highest threat level.
There are currently no variants anywhere in the world classified as VOHC, and in the United States only Delta and Omicron are listed as VOCs.
The following description of variant classifications comes from the CDC:
How Variants Are Classified
The US Department of Health and Human Services (HHS) established a SARS-CoV-2 Interagency Group (SIG) to improve coordination among the Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), Food and Drug Administration (FDA), Biomedical Advanced Research and Development Authority (BARDA), and Department of Defense (DoD). This interagency group is focused on the rapid characterization of emerging variants and actively monitors their potential impact on critical SARS-CoV-2 countermeasures, including vaccines, therapeutics, and diagnostics.
The SIG meets regularly to evaluate the risk posed by SARS-CoV-2 variants circulating in the United States and to make recommendations about the classification of variants. This evaluation is undertaken by a group of subject matter experts who assess available data, including variant proportions at the national and regional levels and the potential or known impact of the constellation of mutations on the effectiveness of medical countermeasures, severity of disease, and ability to spread from person to person. Given the continuous evolution of SARS-CoV-2 and our understanding of the impact of variants on public health, variants may be reclassified based on their attributes and prevalence in the United States.
- Variants Being Monitored (VBM)– View current VBM in the United States that continue to be monitored and characterized by federal agencies
- Variant of Interest (VOI)– Currently, there are no SARS-CoV-2 variants that are designated as Variants of Interest
- Variant of Concern (VOC)– View current VOC in the United States that are being closely monitored and characterized by federal agencies
- Variant of High Consequence (VOHC)– Currently there are no SARS-CoV-2 variants that rise to the level of high consequence
The status of variants often change, and some VOIs and VOCs we were watching over the summer have been purged from the list as Delta totally dominated them this fall.
VOCs are defined by the CDC as:
Variant of Concern (VOC)
A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.
Possible attributes of a variant of concern:
In addition to the possible attributes of a variant of interestVariants of concern might require one or more appropriate public health actions, such as notification to WHO under the International Health Regulations, reporting to CDC, local or regional efforts to control spread, increased testing, or research to determine the effectiveness of vaccines and treatments against the variant. Based on the characteristics of the variant, additional considerations may include the development of new diagnostics or the modification of vaccines or treatments.
- Evidence of impact on diagnostics, treatments, or vaccines
- Widespread interference with diagnostic test targets
- Evidence of substantially decreased susceptibility to one or more class of therapies
- Evidence of significant decreased neutralization by antibodies generated during previous infection or vaccination
- Evidence of reduced vaccine-induced protection from severe disease
- Evidence of increased transmissibility
- Evidence of increased disease severity
While we've yet to see a VOHC (Variant of High Consequence) - and hopefully never will - the CDC's criteria for inclusion in this category are:
Variant of High Consequence (VOHC)
A variant of high consequence has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants.
Possible attributes of a variant of high consequence:
In addition to the possible attributes of a variant of concern
- Impact on Medical Countermeasures (MCM)
- Demonstrated failure of diagnostic test targets
- Evidence to suggest a significant reduction in vaccine effectiveness, a disproportionately high number of infections in vaccinated persons, or very low vaccine-induced protection against severe disease
- Significantly reduced susceptibility to multiple Emergency Use Authorization (EUA) or approved therapeutics
- More severe clinical disease and increased hospitalizations
A variant of high consequence would require notification to WHO under the International Health Regulations, reporting to CDC, an announcement of strategies to prevent or contain transmission, and recommendations to update treatments and vaccines.
