On 20 September 2020, a new strain of Covid-19 was isolated from a sample provided by a person in Kent. This sample was being analysed at the time at Public Health England’s Lighthouse Laboratory in Milton Keynes. The whole genome sequence, or complete set of genetic information as represented by the sequence of its constituent nucleotide molecules, of the new variant was identified by mid-October. But this was was no ordinary variant, incorporating as it did an unprecedented total of seventeen mutations, including eight in the gene encoding the all-important coronavirus surface spike protein. By early December 2020, it had become apparent to scientists that VUI 20201/01 (“first variant under investigation in December 2020), since renamed B.1.1.7, was spreading rapidly, especially in the county of Kent where it was first recognised.
Then came an unexpected and rather cruel blow. On 18 December 2020, the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) informed the UK government about the rapid transmissibility of the mutant, when compared with the dominant strain of virus in the nation. Inevitably, this information prompted a change of official direction. Two days later, Prime Minister Boris Johnson reintroduced restrictive Tier Four coronavirus regulations in London as well as in much of south-eastern England, and was forced to reduce his much-promised relaxation of the lockdown over the Christmas period, complete with “festive bubbles”, to just one day-25 December itself.
Mutations are random and unpredictable events, which are a normal, and expected, feature of viral epidemics and pandemics. They are caused by errors in copying of viral nucleic acid (DNA or RNA) during replication of the virus, and are frequently silent or not readily identifiable, except by genomic testing. In some instances, the virulence and transmissibility of the virus may even be reduced after it mutates. On the other hand, a mutation can also represent a method the virus employs to deal with existential threats, a form of adaptation to an increasingly hostile environment. Many mutations can coexist, leading to a diverse population of viruses at any given time. The only way to keep up with mutations is through continued studies of the genomes of samples from this population. Either way, a high mutation rate provides the virus an effective means to evade the human body’s immune defences, which may struggle to keep up with the changing viral armamentarium.
The new strain was identified by Covid-19 Genomics UK (COG-UK), a consortium of the four public health agencies, the Wellcome Sanger Institute in Cambridge, and twelve British academic institutions. This is by no means the first time Covid-19 has mutated, and more mutations are likely. For example, the D614G variant was detected as early as January 2020, and rapidly became the dominant viral strain in Europe, before establishing itself in North America and Australia.
Unfortunately, when it comes to Covid-19, our information about the novel coronavirus is necessarily incomplete and subject to rapid update. As usual, various experts have stepped into the information void, providing conflicting information about the transmissibility or ease of spread of the new variant (as measured by the R rate), its likelihood of causing severe illness and even death, and its susceptibility to treatment and vaccination, thereby adding further to the confusion.
In the meantime, as scientists attempt to better characterise the new coronavirus strain, model its spread, and study its outcomes, the damage has already been done. Christmas, the biggest holiday of the year, has been severely curtailed, lockdown restrictions have been enhanced, and travel between the UK and at least other countries prohibited, leading to (at the time of writing) at least three thousand lorries being stranded in Kent en route to the Continent. Just as we were looking to reap the benefits of new Covid-19 vaccines, the wily virus has struck yet another blow. The battle may be slowly moving towards the end, but is yet far from over.
Ashis Banerjee