The Delta variant of the SARS-Cov-2 (the Covid-19 virus) has been acknowledged by virologists and epidemiologists as the globally most dominant and transmissible one. Technically known as the B.1.617.2, the Delta variant was first detected in India in December last year. Within months of its discovery, it spread to some 98 nations. Latest reports say, the Delta variant of the pandemic has meanwhile spread to some 132 countries. In the USA more than 83 per cent of the reported cases of the infection are from this variant while it is around 90 per cent in the UK. Similar results would be found in the case of Bangladesh if any study is conducted now. For a study conducted in June by the international centre for diarrhoeal diseases research, Bangladesh (icddr, b) showed that 68 per cent of the cases they studied carried Delta variant. Another study done earlier by the government body, Institute of Epidemiology, Disease Control and Research, (IEDCR), found around 80 per cent of the cases to be infected by the Delta variant.
The high transmissibility of this particular variant of the Covid-19 disease has been proved through tests in the most advanced laboratories of the world. The American Society for Microbiology (ASM), for example, in a recent report said, "Delta is 40-60 per cent more transmissible than Alpha and almost twice as transmissible as the original Wuhan strain of SARS-Cov-2". It may be noted that the Alpha (B.1.1.7) variant was first detected in the UK in November 2020. The Beta variant (B.1.351), on the other hand, was first found in South Africa in December 2020. Similarly, the Gamma variant (P.1) was found among travellers from Brazil in early January this year as they were undergoing routine tests at an airport in Japan. In a similar vein, what a Chinese study found was indeed concerning. The viral load in the case of Delta infection, the Chinese study says, is around 1000 times higher than infections caused by other variants. But these four variants of the Covid-19 virus are not the only ones circulating among the people across the globe. In fact, there are other variants. However, it has been observed by scientists that the transmissibility of these four variants is more than others. So, they have been classified as the Variants Of Concern (VOC) by US scientists monitoring ongoing mutations of the SAARS-Cov-2 virus and its variants in existence there.
It may be noted that the transmission rate of a virus increases manifold among unvaccinated populations. This provides a fertile field for the virus to mutate more often. And according to the American evolutionary biologist Dr. Vaughn Cooper,"The more infections, the more chance that mutations will occur and thus the more likely selection will enrich the best mutations to improve the virus". So, the best way to stop that from happening is increased vaccination.
Given its low rate of vaccination, Bangladesh, as it has planned, should go ahead with its massive vaccination programme. That is more so because, Delta, the worse variant of the virus so far, is now raging across the land. The target should be to slow down, if not stop right away, the rate of infection among the populace. The infection rate must be curbed to reduce mutability of the virus so a more dangerous mutant may not emerge. As the director of WHO's health emergency programme, Michael J. Ryan, recently said, Delta was a wake-up call for humanity as more virulent version of the SAARS-Cov-2 might be in the offing.
The World Health Organisation (WHO) has an ambitious plan to vaccinate 10 per cent of the world population by September and 40 per cent by the end of this year. This is definitely a praiseworthy move by WHO. But the advanced nations will be required to lend a more generous hand in WHO's effort. That will be of great help for countries like Bangladesh to expedite their efforts to reduce the vaccine coverage gap faster.