In the throes of the Covid-19 outbreak, individuals and governments worldwide are turning to science for answers.
The last global outbreak to cause this much panic was the Spanish flu, which is estimated to have killed 50 million and infected 500 million people between 1918 and 1919. The cause of that disease was at the time unknown. By contrast, the viral agent of Covid-19 was discovered just weeks after the outbreak was first detected in China in December 2019. The genome sequence of the virus was made publicly available, allowing hundreds of projects to begin searching for a preventative vaccine. Potential curative drugs could also be considered based on the knowledge of viral structure that the genome sequence yielded and one, remdesivir, is showing promise in trials in China and the US.
Some publishers of scientific literature, such as Elsevier, Wiley and Springer Nature, which are often vilified for charging readers exorbitant sums of money to access their content, have lifted fees on Covid-19 related research. Thousands of scientific studies on the virus have already been published, many using the relatively new concept of “preprint”, where data is made available to readers before undergoing the peer-review process that underpins scientific rigor.
Fast-tracked publications, however, invite problems of their own. The most recent example is the publication of a paper by Chinese scientists arguing that Covid-19 had already mutated into a more virulent form. The researchers sequenced 103 Sars-Cov-2 viruses isolated from different patients infected with the disease. From this, the authors claimed to have identified two different types of the virus, based on small variations in the approximately 30,000 chemical bases called nucleotides that comprise the Covid-19 virus’s genome. One form of virus – the “L” form – was more common than the other, the so-called “S” form. Yet the “S” form appeared in some of the earlier samples. It was concluded that the mutation must have made the common “L” form more virulent.
The report gained widespread media attention and caused significant alarm among members of the public. But as researchers at the University of Glasgow’s Centre for Virus Research have pointed out, the conclusions of the study are unsound and should be read with caution. There is no solid evidence of the virus mutating to increased virulence at all.
However, it is normal for RNA (ribonucleic acid) viruses such as Sars-Cov-2 to acquire random mutations. It may be that the virus becomes less virulent as humans are increasingly exposed to it. Evolution favors those viruses that survive, which involves a complex relationship between virus replication and host immunity. Covid-19 is much more widespread than the Sars outbreak of 2002-03, because it is less virulent and more transmissible. Unlike Sars, Covid-19 spreads before causing the host serious illness or death.
The human genome also shapes the evolutionary battle between virus and host. Why are some people worse affected by Covid-19 (and other viruses) than others? Estimates of the fatality rate vary from country to country. At the time of writing it seems that in Italy, 6.2 percent of those who become infected with coronavirus will die, while in South Korea it is 0.8 percent.