Worrisome variants, widespread easing of appropriate behavior of COVID-19 have sparked new waves of transmission
If manuscripts are copied by hand several times, misspellings are common. Likewise, when “genetic scripts” encoded in DNA or RNA are copied repeatedly for virus replication, errors occur. RNA viruses are more error prone than DNA viruses. The SARS-CoV-2 genome is single-stranded RNA, and mistakes – in biology, mutations – frequently occur.
SARS-CoV-2 is new to humans and as it spreads mutations are very common. Emerging variants with higher transmission efficiency are becoming dominant, tending to replace others. These pioneers are emerging in different geographic communities where the virus is epidemic and is spreading widely. Variants have been detected in the UK and South Africa because genetic studies have been routinely done. The Brazilian variant was discovered in Japan, among travelers from Brazil, and its origin dates back.
The ability to detect and track variants depends on the ability of the laboratory for whole genome sequencing of viruses. To date, more than one million SARS CoV-2 genomes have been sequenced worldwide, providing a granular spatiotemporal readout of virus evolution at high resolution. More importantly, this allowed the identification and documentation of variant viruses with altered properties from the virus that triggered the pandemic. The importance of “ variants of concern ” (VOCs) having been appreciated, the Indian SARS CoV-2 Genomic Consortium (INSACOG), a network of ten public laboratories competent for genomic surveillance, was created, and the variant landscape was created. genetics is under development. investigated in India.
There are three different nomenclature schemes for SARS-CoV-2 variants. The most widely used is “phylogenetic attribution of global epidemic lines” (PANGOLIN) which uses a hierarchical system based on genetic relatedness – an invaluable tool for genomic surveillance. It uses alphabets (A, B, C, P) and numbers starting with 1. Variant lineages are at the emerging edge of the pandemic in different geographic areas. Line B is the most prolific. The variants in circulation are B.1; B.1.1; B.1.1.7; B.1.167; B.1.177; B.1.351, B.1.427 and B.1.429. The P.1 line has deviated from the original B.
For convenience, the three most common are named by their original geography – “British variant” for B.1.1.7; “South Africa variant” for B.1.351; and “Brazil variant” for P.1. They had been detected in 2020 – September (United Kingdom), October (South Africa) and December (Brazil). Variants in India include the so-called double mutant B.1.617 spreading in Maharashtra and B.1.618 spreading in West Bengal.
Mutations can be localized using the position of the nucleotides on the genome and the switched amino acids subsequent to the mutation. The original pandemic virus (founder variant) was Wu.Hu.1 (Wuhan virus). Within months, the D614G variant appeared and became dominant globally.
The “concern” in VOCs includes three sinister properties – the efficiency of transmission, the severity of the disease, and the immune coverage escape from vaccination.
In many countries, including India, VOCs, due to increased transmissibility, have triggered one or more new waves of epidemic transmission. Unfortunately, at this precise point in time, as the number of cases was low, there was widespread relaxation of appropriate behavior for COVID. Together, this contributed to a rapidly rising second wave – the daily numbers far exceeding those of the previous wave.
When it comes to virulence (propensity to cause serious / life-threatening illness), the UK variant is worse. The South African and Brazilian variants do not appear to have higher virulence.
The third concern is the immune coverage offered by vaccination using antigens made from the D614G variant – which applies to most vaccines currently in use. Lower vaccine efficacy was observed more with the South African variant and less with the Brazilian variant. Therefore, reinfection may occur despite immunity by D614G infection or earlier vaccination. The vaccine’s efficacy may be lower now than determined in phase 3 trials because VOCs were not widespread then. Fortunately, mRNA vaccines (Pfizer and Moderna) have broader immunity for different reasons, and they protect better against these two variants.
The Karolinska Institute in Sweden created an antigen using a new RBD variant peptide with adjuvant, and inoculated monkeys already primed with an older vaccine. The resulting booster response was not only high but also broad, covering new variations. This approach, called “hetero-boosting” by a different vaccine, offers a way to deal with “vaccine leak” variants until new vaccines become available.
An important lesson that the pandemic has taught us in India is the critical importance of biomedical research and capacity building – for saving lives and economic growth. We need a large-scale research base, in universities, medical schools and biotechnology companies, all of which need to be funded, encouraged, appreciated and rewarded by talent. Although some efforts have been launched, they must take off and India must invest heavily in the biosciences. After a decade, its products and benefits will make us healthier and richer.
(T. Jacob John is a retired professor, and Mahesh Moorthy is currently professor, Department of Clinical Virology, Christian Medical College, Vellore.)