DELTA AND DELTA PLUS VARIANTS: FREQUENTLY ASKED QUESTIONS
Ministry
of Health and Family Welfare
DELTA AND DELTA PLUS
VARIANTS: FREQUENTLY ASKED QUESTIONS
Posted On: 28 JUN 2021
2:52PM by PIB Mumbai
New Delhi / Mumbai, 28th June, 2021
Vaccines and COVID
Appropriate Behaviour can help us fight the pandemic.
Secretary, Department
of Biotechnology; Director General, Indian Council of Medical Research; and
Director, National Centre for Disease Control have answered many questions
about the Delta
and Delta Plus variants of the SARS-Cov-2 virus. PIB has curated the answers,
given at a COVID Media Briefing held by the Health Ministry on June 25, 2021.
Q. Why does a virus mutate?
Virus by its very nature mutates. It is part of its evolution.
The SARS-Cov-2 virus is a single-stranded RNA virus. So, changes in the genetic
sequence of the RNA are mutations. The moment a virus enters its host cell or a
susceptible body, it starts replicating. When the spread of infection
increases, the rate of replication also increases. A virus that has got a
mutation in it is known as a variant.
Q. What is the impact of
mutations?
The normal process of
mutations begins to impact us when it leads to changes in transmission levels
or on treatment. Mutations can have positive, negative or neutral effects on
human health.
Negative impacts include clustering
of infections, increased transmissibility, ability to escape immunity and
infect someone who has prior immunity, neutralization escape from monoclonal
antibodies, improved binding to lung cells and increased severity of infection.
Positive impacts can be
that the virus becomes non-viable.
Q. Why are frequent mutations seen in SARS-CoV-2 virus? When will
the mutations stop?
SARS-CoV-2 can mutate due to the following
reasons:
·
Random
error during replication of virus
·
Immune pressure faced by viruses after
treatments such as convalescent plasma, vaccination or monoclonal antibodies
(antibodies produced by a
single clone of cells with identical antibody molecules)
·
Uninterrupted transmission due to lack of
COVID-appropriate behaviour. Here the virus finds excellent host to grow and
becomes more fit and more transmissible.
The virus will continue
to mutate as long as the pandemic remains. This makes it all the more crucial
to follow COVID appropriate behavior.
Q. What are Variants of Interest
(VoI) and Variants of Concern (VoC)?
When the mutations
happen – if there is any previous association with any other similar variant
which is felt to have an impact on public health – then it becomes a Variant
under Investigation.
Once genetic markers are
identified which can have association with receptor binding domain or which
have an implication on antibodies or neutralizing assays, we start calling them
as Variants of Interest.
The moment we get
evidence for increased transmission through field-site and clinical
correlations, it becomes a Variant of Concern. Variants of concern are those
that have one or more of the following characteristics:
·
Increased
transmissibility
·
Change
in virulence/ disease presentation
·
Evading
the diagnostics, drugs and vaccines
The
1st Variant of Concern was announced by the UK where it was found. Currently
there are four variants of concern identified by the scientists - Alpha, Beta,
Gamma and Delta.
Q. What are Delta and Delta Plus
variants?
These are the names
given to variants of SARS-CoV-2 virus, based on the mutations found in them.
WHO has recommended using letters of the Greek Alphabet, i.e., Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617), etc., to denote
variants, for easier public understanding.
Delta variant, also
known as SARS-CoV-2 B.1.617, has about 15-17 mutations. It was first reported
in October 2020. More than 60% of cases in Maharashtra in February 2021
pertained to delta variants.
It
is the Indian scientists who identified the Delta Variant and submitted it to
the global database. Delta variant is classified as a Variant of
Concern and has now spread to 80 countries, as per WHO.
Delta variant (B.1.617)
has three subtypes B1.617.1, B.1.617.2 and B.1.617.3, among which B.1.617.1 and
B.1.617.3 have been classified as Variant of Interest, while B.1.617.2 (Delta
Plus) has been classified as a Variant of Concern.
The Delta Plus variant
has an additional mutation in comparison to Delta variant; this mutation has
been named as the K417N mutation. ‘Plus’ means an additional mutation has happened
to the Delta variant. It does not mean that the
Delta Plus variant is more severe or highly transmissible than the Delta
variant.
Q. Why has the Delta Plus Variant
(B.1.617.2) been classified as a Variant of Concern?
The Delta Plus variant
has been classified as Variant of Concern because of the following
characteristics:
·
Increased
transmissibility
·
Stronger
binding to receptors of lung cells
·
Potential
reduction in monoclonal antibody response
·
Potential
post vaccination immune escape
Q. How
often are these mutations studied in India?
Indian SARS-CoV-2
Genomics Consortium (INSACOG) coordinated by the Department of Biotechnology
(DBT) along with Union Health Ministry, ICMR, and CSIR monitor the genomic
variations in the SARS-CoV-2 on a regular basis through a pan India
multi-laboratory network.
It was set up with 10 National Labs in
December 2020 and has been expanded to 28 labs and 300 sentinel
sites from where genomic samples are collected. The INSACOG hospital network
looks at samples and informs INSACOG about the severity, clinical correlation,
breakthrough infections and re-infections.
More than 65,000 samples
have been taken from states and processed, while nearly 50,000 samples have
been analysed of which 50% have been reported to be Variants of Concern.
Q. On what basis are the samples subjected to Genome Sequencing?
Sample selection is done
under three broad categories:
1)
International passengers (during the beginning of the Pandemic)
2) Community
surveillance (where RT-PCR samples report CT Value less than 25)
3) Sentinel surveillance
- Samples are obtained from labs (to check transmission) and hospitals (to check
severity)
When
there is any public health impact noticed because of genetic mutation, then the
same is monitored.
Q. What is the trend
of Variants of Concern circulating in India?
As per the latest data,
90% of samples tested have been found to have Delta Variants (B.1.617).
However, B.1.1.7 strain which was the
most prevalent variant in India in the initial days of the pandemic has
decreased.
Q. Why public health action is not
taken immediately after noticing mutations in virus?
It is not possible to say whether the mutations
noticed will increase transmission. Also, until there is scientific evidence
that proves a correlation between rising number of cases and variant
proportion, we cannot confirm there is a surge in the particular variant. Once
mutations are found, analysis is made week on week to find if there is any such
correlation between the surge of cases and variant proportion. Public health
action can be taken only after scientific proofs for such correlation are
available.
Once such correlation is
established, this will help greatly to prepare in advance when such variant is
seen in another area/region.
Q. Do COVISHIELD and COVAXIN work
against the variants of SARS-CoV-2?
Yes, COVISHIELD and
COVAXIN are both effective against the Alpha, Beta, Gamma and Delta variants.
Lab tests to check vaccine effectiveness on Delta Plus Variant are ongoing.
Delta Plus Variants: The
virus has been isolated and is being cultured now at ICMR’s National Institute
of Virology, Pune. Laboratory tests to check vaccine effectiveness are ongoing
and the results will be available in 7 to 10 days. This will be the first
result in the world.
Q. What are the public health
interventions being carried out to tackle these variants?
The public health
interventions needed are the same, irrespective of the variants. The following
measures are being taken:
·
Cluster
containment
·
Isolation
& Treatment of cases
·
Quarantining
of contacts
·
Ramping
up vaccination
Q. Do public health strategies change as the virus mutates and more
variants arise?
No, public health prevention
strategies do not change with variants.
Q. Why is continuous monitoring of mutations important?
Continuous monitoring of
mutations is important to track potential vaccine escape, increased
transmissibility and disease severity.
Q. What does a common man do to protect him/her from these Variants
of Concern?
One must follow COVID
Appropriate Behaviour, which includes wearing a mask properly, washing hands
frequently and maintaining social distancing.
The second wave is not
over yet. It is possible to prevent a big third wave provided individuals and
society practise protective behaviour.
Further, Test Positivity
Rate must be closely monitored by each district. If the test positivity goes
above 5%, strict restrictions must be imposed.
Dhanalakshmi/DJM/DY/PIB Mumbai /pibmumbai pibmumbai@gmail.com
(Release ID: 1730875)
