Posts Tagged with “Omicron COVID-19 virus”
SARS-CoV-2 Variant-Omicron-omicron symptoms and severity
What is Omicron and what makes it a variant of concern (VoC)?
It is a new variant of SARS-CoV-2 that has recently been reported from South
Africa on 24th November 2021 called as B.1.1.529 or Omicron (based on Greek
alphabets like alpha, beta, delta etc).
This variant has shown a very large number of mutations, especially more than 30 on the viral spike protein, which
is the key target of the immune response.
Given the collection of mutations in Omicron, which earlier individually have
been associated with increased infectivity and/or immune evasion, and the
sudden rise in number of positive cases in South Africa, World Health
Organization has declared Omicron as a Variant of Concern (VoC).
Can the currently used diagnostics methods, detect Omicron?
The most accepted and commonly used method of diagnostic for SARS-CoV2 Variant is RT-PCR method. This method detects specific genes in the virus,
such as Spike (S), Enveloped (E) and Nucleocapsid (N) etc to confirm the presence of virus. However, in case of Omicron, as the S gene is heavily mutated, some of the primers may lead to results indicating absence of the S
gene (called as S gene drop out).
This particular S gene drop out along with the detection of other viral genes could be used a diagnostic feature of Omicron. However, for final confirmation of the omicron variant genomic sequencing is
How concerned should we be about the new VoC?
WHO declares a variant as a VoC after assessment when there is 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. (Source: WHO)
It is important to highlight that Omicron has been declared VoC based on the
observed mutations, their predicted features of increased transmission and
immune evasion, and preliminary evidence of detrimental change in COVID-19
epidemiology, such as increased reinfections. The definitive evidence for
increased remission and immune evasion is awaited.
What precautions should we take?
The precautions and steps to be taken remain same as before. It is essential
to mask yourself properly, take both doses of vaccines (if not yet vaccinated),
maintain social distancing and maintain good ventilation to the maximum
Will there be a third wave?
Omicron cases are increasingly being reported from countries outside of South
Africa and given its characteristics, it is likely to spread to more countries
including India. However, the scale and magnitude of rise in cases and most
importantly the severity of disease that will be caused is still not clear.
Further, given the fast pace of vaccination in India and high exposure to delta variant as
evidenced by high seropositivity, the severity of the disease is anticipated to be
low. However, scientific evidence is still evolving.
Will the existing vaccines work against Omicron?
While, there is no evidence to suggest that existing vaccines do not work on
Omicron, some of the mutations reported on Spike gene may decrease the
efficacy of existing vaccines. However, vaccine protection is also by antibodies
as well as by cellular immunity,
which is expected to be relatively better preserved. Hence vaccines are expected to still offer protection against severe
disease and, vaccination with the available vaccines is crucial.
If eligible, but not vaccinated, one should get vaccinated.
How is India responding?
Indian government is monitoring the situation closely and is issuing suitable
guidelines from time to time. Meanwhile, the scientific and medical community
is geared up for developing and deploying diagnostics, carrying out genomic
surveillance, generating evidence about viral and epidemiologic characteristics,
and development of therapeutics.
Why do variants occur?
Variants are normal part of evolution and as long as the virus is able to infect,
replicate and transmit, they will continue to evolve.
Further, not all variants are dangerous and most often than not, we don’t notice them. Only when they are
more infectious, or can reinfect people etc they gain prominence.
The most important step to avoid generation of variants is to reduce the number of
Source:WHO and MoHFW, GoI