2. Classifications
Variant of interest (VOI)
Variant of Concern (VOC)
Variant of high consequence (VOHC)
Variants being monitored (VBM)
3. VOI
Changes to receptor binding domain
Reduced neutralization by antibodies generated against previous
infection or vaccination
Reduced efficacy of treatment, or tests
Predicted increase in transmissibility or disease severity
It usually has limited prevalence
Action taken by CDC – Increase in surveillance or epidemiological
investigation
4. VOC
Increase in transmissibility
More severe disease
Significant reduction in neutralization by antibodies generated
during previous infection or vaccination
Reduced effectiveness of treatments/vaccines/diagnostic
detection failure
Action taken:
NotifyWHO and CDC, increased preventive measures, research to
determine effectiveness of vaccine and treatment
5. Variant of high
consequence
(VOHC)
Demonstrate failure of diagnostic test targets
Significant reduction in vaccine effectiveness
Significant reduction in therapeutic measures effectiveness
More severe disease and increased hospitalization
Action taken: NotifyWHO and CDC, announcements of strategies to
prevent or contain transmission, Recommendations to update
treatments and vaccines
6. Variants being
monitored
(VBM)
Data indicates clear impact on available countermeasures
Causes severe disease or increased transmission but no longer
detected
Previously designated asVOI,VOC orVOHC and currently
circulating in low levels in USA
7. List of variants
Gamma P.1 VBM
Delta B.1.617.2 VBM
OMICRON B.1.1.529 and
descendants
VOC on 26 Nov 2021
WHO label Pango lineage Current status
Alpha B.1.1.7 VBM
Beta B.1.351 VBM
9. Key terms
Mutation: Single change in viral genome
Lineage:Grp of closely related viruses with common ancestor.All
lineages of SARS CoV 2 causes Covid 19
Sublineage: Example is BA.2.75 is a sublineage of BA.2. Direct
descendent from parent lineage
Variant:Genome contain one or more mutations. ExampleVOI/
VOC/VOHC/VBM
Recombinant:Two variants genome combine during replication to
form new variant (recombinant) different from both parent
lineages.Can occur if a person infected with both variants at a
time.
10. Pango lineage
system
Hierarchical like family tree
Lineages are evolutionary descendants of a parent lineage
Named using alphabetical prefix and numerical suffix
11. Nextclade
Tool to classify sequences as per there genetic relatedness
Potentially important branches of family tree are given names
indicating that they a (clade) arising from same ancestor.
Name consists of 2 digit year of assignment followed by a letter
indicating order of assignment within the year.
