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Source, spread and vaccine race of C-19

Published : Monday, 23 November, 2020 at 12:00 AM  Count : 228

Source, spread and vaccine race of C-19

Source, spread and vaccine race of C-19

The single biggest threat to man's continued dominance on the planet is the virus. Peter Medawar, a British Biologist and a Nobel laureate, who was known as the 'father of transplantation' once said, 'A virus is a piece of bad news wrapped in protein'. Lewis Thomas, known as a poet-philosopher of medicine goes further and said, 'we live in a dancing matrix of viruses; they dart, rather like bees, from organism to organism, from plant to insect to mammal to me and back again, and into the sea, tugging along pieces of this genome, strings of genes from that, transplanting grafts of DNA, passing around heredity as though at a great party.'  

Thomas suggests that the virus dance in the ecosystem as if they are enjoying themselves in a party. They are the most common, the most diverse, and the fastest-evolving biological entities on Earth. This essay presents some new information about the source of Covid-19, new mode of spread of the disease and the vaccine race.

When we consider the source factor of the Covid-19 disease, we examine both internal and external source factors. In terms of the internal source factor, a report published in the Nature, dated 26 October 2020 suggested that a segment of DNA 50,000 nucleotides long was found to have a strong association with severe COVID-19 infection and hospitalization. This segment of DNA is inherited from Neanderthals. This result not only shed light on the fact that some people are more susceptible to severe Covid-19 disease, but also provides insight into human evolutionary biology. In terms of the external source factor, Wuhan Institute of Virology did the genetic sequence of SARS-COV-2 and the virus found in the horseshoe bat (scientific name Rhinolophus affinis) in caves in Yunnan on 24 July 2013. They gave the name of the virus as RaTG13. This virus that was discovered in 2013 is 96% identical to SARS-COV-2. My personal view is that China was well aware about the virus before anybody else.

There was a news circulated at the beginning of 2020 that virus was transmitted through pangolins to human. But the sampling of viruses in pangolin shows a small section of their genome similar to SARS-COV-2. This suggests that Pangolin is not the primary source of transmission from bat to human, because the full genetic sequence of SARS-COV-2 was not found in Pangolin. This raise further question that there might have another source where direct transmission of the virus to human is probable. According to the US Centre for Disease Control and Prevention, between 1997 and 2006, 17 people in the US caught rabies from bats. Most of these people reported handling a bat. Rabies cannot be passed from person to person directly but SARS-COV-2, a highly transmissible virus can pass. But human can come into contact with bats in many other ways, including research, pest control, wildlife rehabilitation and visiting recreational caves. Time will tell more about this issue.

The spread of coronavirus has been taken into different dimensions recently. The research suggests that the virus can spread back and forth between humans and animals. It has been discovered that Mink, a type of carnivorous mammals in Denmark are spreading a mutant forms of coronavirus. The New Scientist (14 November 2020 issue) has informed that 'the human-mink-human transmission chain demonstrates the real and present danger of what virologists call "reverse spillover" and "spillback".' In the meantime, all 17 Million farmed mink in Denmark were put at risk of being slaughtered. Almost 60 species of mammal have so far been found to be susceptible to SARS-COV-2. These include, in addition to the other species, domestic cow, goat, sheep, horse, dog and cats.

The vaccine race is ongoing and it will continue next year as well. A survey conducted recently by University College London of 70000 British adults suggests that only around half would be very likely to take a Covid-19 vaccine, while a significant numbers registered their concerns about the vaccine. Out of other half of the sample, 53% believe that vaccines can cause unforeseen side effects, 38% believe natural immunity is better than a vaccine and 25% believe vaccines are used for commercial profiteering. When safety and efficacy of the vaccine use is confirmed, then the next challenge is distribution. The UK has taken the unprecedented step of pre-ordering millions of doses from six companies. As far as we know, European Union has pre-ordered 1.3 billion doses and on behalf of the poorer countries UNICEF has pre-ordered 520 million doses.

UK has secured early access to 355 million vaccine doses through agreements with several separate vaccine developers. These are as follows: 100 million doses of University of Oxford and Astra Zeneca vaccine, 40 million doses of BioNTech/Pfizer vaccine, 60 million doses of Novavax vaccine, 60 million doses of Valneva vaccine, 60 million doses of GSK/Sanofi Pasteur vaccine, 30 million doses of Janssen vaccine and 5 million doses of the Moderna vaccine.

Two vaccines are ahead of other vaccine preparations: Pfizer vaccine and Moderna vaccine. Pfizer initially mentioned that their vaccine is 90% effective, but later on declared that their vaccine is 95% effective in protecting against Covid-19. Moderna vaccine has been cited as 94.5% effective in protecting against Covid-19. Both of them are known as RNA vaccine. The key difference is how they need to be stored. Pfizer vaccine requires extremely low temperature of around minus 70 degree centigrade but can be kept in the fridge for five days. The Moderna vaccine remains stable at minus 20 degree centigrade for up to six months and can be kept in a normal fridge for up to a month. Both of these vaccines work in human body similar ways.

First the vaccine is produced in a laboratory by taking part of the genetic code (RNA) of the virus and coating it in a lipid, so it can enter the body's cells. Second, the RNA enters the cells and provides instructions to produce the Covid-19 spike protein. Third, this prompts the immune system to produce antibodies and activate T-cells to destroy infected cells. Fourth, if the patient encounters Covid-19 the antibodies and T-cells are triggered to fight the virus.  Very recently Oxford Group informed that their vaccine is 95% effective for 60 and above age group. So, vaccine developers are trying to target their users group. According to the WHO, there are currently 46 candidates of vaccine developers who are doing clinical trials. Out of them seven vaccines are in phase III stages.

Above all, the association between the Neanderthal's segment of DNA and severe Covid-19 disease suggests that our ancestors can take some blame for how someone responds to the viruses. But other social and behavioural factors also play a part.  Our domestic animals also can carry coronavirus and spread it to humans. Regarding vaccine development, we see some light at the end of the tunnel, but safety and efficacy are two important indicators should not be compromised, in order to gain public confidence about the vaccine. We are also facing new problem, known as 'long covid'. This is the debilitating syndrome that follows a coronavirus infection. Breathlessness, pain, fatigue, blood clots, organ damage-these are some of the symptoms and complications ascribed to 'long covid'.

The National Health Service in UK has launched a network of more than 40 'long covid' specialist clinics to help thousands of patients suffering from the debilitating effects of the virus months after being infected.  It is a cautionary message to all of us to do what we can to prevent infection. We all should remember that 'our task is to understand what this disease means to the lives of those it has afflicted and to use that understanding not only to change our perspective on the world but also to change the world itself'.
The writer is a UK based academic, chartered scientist and environmentalist, columnist and author




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