Scientists across the world are trying to develop a line of treatment and a possible vaccine for COVID-19, the disease caused by the novel coronavirus, which has infected over 100,000 people and claimed over 4,000 lives. Even the most optimistic timelines, however, don’t see a line of treatment or vaccine arriving before next year. Meanwhile, a global effort is on to collect and analyse the genetic composition of the new virus, which would be key to developing a cure and a vaccine.
Coronavirus outbreak: What kind of genetic information is being studied?
Laboratories in various countries have been isolating and sharing the genome sequences of the virus on an international platform. Whole genome sequencing is the process of determining the complete DNA sequence of an organism’s genome at a single time. Genome sequence is the unique code of genetic material of any organism, and determines the characteristic of any organism. The gene composition of novel coronavirus, for instance, is different from that of the influenza virus. Every organism has a unique genome sequence.
So far, 326 sets of data have been shared. India has so far reported two sets of genome sequences, both of which are very similar to the original sequences collected from patients in Wuhan. Scientists say this is expected since the sequences were extracted from the first positive cases in Kerala, who had returned from Wuhan. China has contributed 120 sequences.
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So, why are so many genome sequences being isolated?
When viruses multiply, or reproduce, there is a copying mechanism that transfers the gene information to the next generation. However, no copying mechanism is perfect. When the virus multiplies, there will be small changes, which are called mutations. These mutations accumulate over time, and after prolonged periods, are responsible for evolution into new organisms. Within a single reproduction, the changes are extremely minor. More than 95 per cent of the gene structure remains the same.
However, the small changes that occur are crucial to understanding the nature and behaviour of the organism. In this case, for example, the small changes could provide scientists with information about the origin, transmission, and impact of the virus on the patient. It could also hold clues to the differing effects the virus could have on patients with different health parameters.
What explains the huge difference between the number of genome sequences contributed by China (120) and India (2)?
India has far fewer positive cases compared to China, South Korea, Iran, Italy, or even the United States. Every day, about 20-30 genome sequences are being shared from different laboratories across the world. Patients who have been infected with the virus in similar conditions are unlikely to show any significant changes in the genome sequences. For example, the positive cases in a group of 40 from Maharashtra, who visited Dubai last month, are likely to have similar genome sequences, and therefore, one or two representative sequencing could be adequate from the group. Patients with existing medical conditions could be other candidates from where genome sequences of this virus could be isolated. This could help scientists to look for clues to possible impact of virus amidst those existing medical conditions.
Some countries have been reporting genome sequences much faster than others. China has contributed 120 sequences so far, but has not been sharing any more for the last few days. The US has shared 43 genome sequences, while the Netherlands and the United Kingdom have contributed 25 each.
Scientists say new technological tools have made it easier to isolate full genome sequences. Traditional techniques used to take weeks for the extraction, but new machines are able to do it within two to three days.
The two Indian sequences have both come from patients who had returned from Wuhan where the outbreak began in December last year.
Currently, what is the most effective medication?
As of now, scientists do not know. The ideal way of testing a drug to show that it is effective is to compare no-treatment to new-treatment in a clinical trial. Using a drug or drugs in one or two persons provides anecdotal evidence.
In trials , data is accumulated from many people. Although several efforts to develop drugs are going on, scientists say success is unlikely to come immediately.
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Right now, drugs are being repurposed, meaning old drugs for similar diseases are being checked for their efficacy against COVID-19. These drugs, if they work, will require clinical trials, and then can be made widely available for people. In most cases, symptomatic treatment for fever, body ache, and cough will be sufficient. More severe cases will require oxygen and respiratory support.
“New drugs will be useful particularly for severe cases, but we will have to wait to see how long it will take to get repurposed drugs and new drugs,” said Dr Gagandeep Kang, Executive Director of the Translational Health Science and Technology Institute.
This article first appeared in the print edition on March 12, 2020 under the title ‘The hunt for corona treatment’.
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