Like all viruses, SARS-CoV-2 also replicate or make copies of itself. In the process of replication, some genetic changes/variations occur. These changes are called “mutations”. A virus with one or more new mutations is referred as “variant” of the original virus.
Most of the mutations don’t change virus’ properties. But sometimes, some changes may affect the virus’s properties such as its transmissibility, severity of disease, effects of therapeutic medicines, vaccines, diagnostic tools, or other public health and social measures depending on where the changes are located in the virus’s genetic material.
Classification of variants (WHO)
The World Health Organization has classified variants as- variant of interest and variant of concern and proposed using labels consisting of the Greek Alphabet, i.e., Alpha, Beta, Gamma, Delta as a practical way to discuss variants by non-scientific audiences.
B.1.617.2, a variant of COVID-19 is known as the Delta variant. It was first identified in October 2020 in India, and was primarily responsible for the second wave in the country.
Variant of Interest (VOI)
Variant of Concern (VOC)
A SARS-CoV-2 variant meets the definition of VOI and is associated with one or more of the following changes concerned with global public health significance:
What causes a virus to change to a new variant?
When a virus is widely circulating in a population, it gets more opportunities to replicate and spread the infection. The more it replicates, the more chances it gets for changes/mutations to occur.
SARS-CoV-2 can mutate due to the following reasons:
How can we prevent future new variants of the COVID-19 virus?
The critical step to prevent the future variants is stopping the spread of virus at the source with following measures:
Follow public health and social measures (PHSM) in the form of:
Vaccinate more people: Vaccination of more and more people will further lead to decrease in virus circulation and in turn fewer mutations. While vaccination is underway, PHSMs needs to be continued.
Why is it important to get vaccinated even if there are new variants of the virus?
Vaccines are a critical tool in the fight against COVID-19. People should get the vaccination even if the vaccines may be somewhat less effective against some of the COVID-19 virus variants. Still all vaccines approved for emergency use protect against developing severe disease, hospitalization and death due to the various variants.
What is the strategy for SARS CoV-2 surveillance in India?
The Indian SARS-CoV-2 Genomics Consortium (INSACOG) has been established by the by the Ministry of Health and Family Welfare, Government of India in December 2020 for the genomic surveillance of SARS CoV-2. INSACOG is a consortium of 28 Regional Genome Sequencing Laboratories (RGSL) of Ministry of Health & Family Welfare, Dept. of Biotechnology, Indian Council of Medical Research (ICMR) and Council of Scientific and Industrial Research (CSIR).
Initially, genomic surveillance was focused on the variants carried by international travelers and their contacts in the community through sequencing 3-5% of the total RTPCR positive samples. Subsequently, the sentinel surveillance (for all States/UTs/) and surge surveillance (for districts with COVID-19 clusters or those reporting a surge in cases) were started in the country.