covid-19: View: Delta variants can’t escape immunity


Dr Vinod Scaria, who works closely with the Maharashtra public health department on the genome surveillance project, tells TOI that the state should be the role model for others because samples were chosen in a scientific manner to ensure every district was covered.

Your team has been studying samples from the two most affected Indian states, Maharashtra and Kerala. Please share your observations about Maharashtra.
The programmes in Maharashtra and Kerala were developed as a collaborative initiative between CSIR and the state governments. There are designed for surveillance, to provide early warning and aid public health policy.

A key observation about Maharashtra is the systematic and uniform genome sequencing across each district. This helped identification of emerging variants and the state government promptly applied public health measures. Maharashtra should be the role model for other states.

The Delta Plus cases in Maharashtra have increased from 21 to 76 in a few days. Can we now say Delta-plus is the variant to watch out for?

While Delta has become the predominant lineage in India and many parts of the world, the virus will continue to evolve by accumulating more genetic mutations. The Delta sub-lineages are popularly called Delta Plus lineages as they have additional mutations in the genomic background of Delta. These sub-lineages are increasing, but the number of cases is not yet significantly large.

Considering Delta has already affected crores of Indians and wreaked havoc across the country during the second wave, can it still cause another wave?

Waves of Sars-CoV-2 infection have occurred across the world as people loosen their vigil and public health measures, and also because the antibody levels from pre-existing infection or vaccines wane over time. While nobody can definitely predict which variant would emerge and cause the next wave, examples from the past from across the globe suggest the same variant could indeed cause multiple waves in a country. As a larger proportion of the population becomes immune through vaccination and/or previous infection, the infections resulting in severe disease and deaths would significantly come down and the infection would become endemic.

What about Delta’s sub-lineages (in terms of their ability to cause a wave)?
There are 13 sub-lineages of Delta as of date (AY.1 to AY.12 and AY.3.1). At this moment, it is not possible to predict which one would cause a wave as it also depends on the susceptible population in the region. However, as none of these emergent sub-lineages can so far fully escape the immunity due to previous infections or vaccines, it is our urgent priority to vaccinate the entire population.

In terms of whole genome sequencing, India still lags way behind the global yardstick of testing at least 5% of all positive samples. What can be done to change this?
It would be improper to directly compare… Currently the genome surveillance strategy in India is very diverse, with some parts over-represented and others highly underrepresented. For the surveillance to be informative and effective, it is important we have a uniform and long-term surveillance strategy for India.


Source link