সহকারী শিক্ষক
০১ ডিসেম্বর, ২০২১ ০৯:৫৬ অপরাহ্ণ
Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern
Omicron (B.1.1.529): SARS-CoV-2 Variant of
Concern
The Technical Advisory Group on SARS-CoV-2 Virus Evolution
(TAG-VE) is an independent group of experts that periodically monitors and
evaluates the evolution of SARS-CoV-2 and assesses if specific mutations and
combinations of mutations alter the behaviour of the virus. The TAG-VE was
convened on 26 November 2021 to assess the SARS-CoV-2 variant: B.1.1.529.
The B.1.1.529 variant was first reported to WHO from South
Africa on 24 November 2021. The epidemiological situation in South Africa has
been characterized by three distinct peaks in reported cases, the latest of
which was predominantly the Delta variant. In recent weeks, infections have
increased steeply, coinciding with the detection of B.1.1.529 variant. The
first known confirmed B.1.1.529 infection was from a specimen collected on 9
November 2021.
This variant has a large number of mutations, some of which
are concerning. Preliminary evidence suggests an increased risk of reinfection
with this variant, as compared to other VOCs. The number of cases of this
variant appears to be increasing in almost all provinces in South Africa.
Current SARS-CoV-2 PCR diagnostics continue to detect this variant. Several
labs have indicated that for one widely used PCR test, one of the three target
genes is not detected (called S gene dropout or S gene target failure) and this
test can therefore be used as marker for this variant, pending sequencing
confirmation. Using this approach, this variant has been detected at faster
rates than previous surges in infection, suggesting that this variant may have
a growth advantage.
There are a number of studies underway and the TAG-VE will
continue to evaluate this variant. WHO will communicate new findings with
Member States and to the public as needed.
Based on the evidence presented indicative of a detrimental
change in COVID-19 epidemiology, the TAG-VE has advised WHO that this variant
should be designated as a VOC, and the WHO has designated B.1.1.529 as a VOC,
named Omicron.
As such, countries are asked to do the following:
enhance surveillance and sequencing efforts to better
understand circulating SARS-CoV-2 variants.
submit complete genome sequences and associated metadata to
a publicly available database, such as GISAID.
report initial cases/clusters associated with VOC infection
to WHO through the IHR mechanism.
where capacity exists and in coordination with the
international community, perform field investigations and laboratory
assessments to improve understanding of the potential impacts of the VOC on
COVID-19 epidemiology, severity, effectiveness of public health and social
measures, diagnostic methods, immune responses, antibody neutralization, or
other relevant characteristics.
Individuals are reminded to take measures to reduce their
risk of COVID-19, including proven public health and social measures such as
wearing well-fitting masks, hand hygiene, physical distancing, improving
ventilation of indoor spaces, avoiding crowded spaces, and getting vaccinated.
For reference, WHO has working definitions for SARS-CoV-2
Variant of Interest (VOI) and Variant of Concern (VOC).
A SARS-CoV-2 VOI is a SARS-CoV-2 variant:
with genetic changes that are predicted or known to affect
virus characteristics such as transmissibility, disease severity, immune
escape, diagnostic or therapeutic escape; AND
that has been identified as causing significant community
transmission or multiple COVID-19 clusters, in multiple countries with
increasing relative prevalence alongside increasing number of cases over time,
or other apparent epidemiological impacts to suggest an emerging risk to global
public health.
A SARS-CoV-2 VOC is a SARS-CoV-2 variant that meets the
definition of a VOI (see above) and, through a comparative assessment, has been
demonstrated to be associated with one or more of the following changes at a
degree of global public health significance:
increase in transmissibility or detrimental change in
COVID-19 epidemiology; OR
increase in virulence or change in clinical disease
presentation; OR
decrease in effectiveness of public health and social
measures or available diagnostics, vaccines, therapeutics