Tracking the Variants

The UK was badly hit, in the first wave of the Covid-19 pandemic. This was because, in February-March 2020, the country was 'seeded' by 1000 different varieties of the virus. The varieties were brought in by people mainly returning from France, Italy and Spain. Viruses 'replicate' quickly and repeatedly, producing massive numbers. Consequently, errors in the sequencing (mutations) are very frequent. Most such mutations have few consequences for the virus or its hosts. Occasionally, however, a variant of concern appears like the Kent, Brazil or South African varieties. Variants may become concerning when their ease of transmission, the severity of the disease condition produced and/or their ability to counter antibodies changes. Spiegelhalter and Masters have detailed how variants are tracked and traced (https://www.theguardian.com/theobserver/commentisfree/2021/mar/07/how-do-we-track-and-measure-new-variants-of-coronavirus). Spiegelhalter and Masters note that the spread of variants of Sars-CoV-2 can be followed by sequencing in Polymerase Chain Reaction (PCR) laboratories. Full sequencing (somewhat slow and expensive) is needed in many cases. Sometimes, however, faster,'proxy' methods are available, such as the S-Gene Target Failure seen in the Kent variant. In this case, the gene can be screened for. Spiegelhalter and Masters note that, around 50% of the sequences of global Sars-CoV-2, have been published by UK labs (it's a speciality). The UK labs have received material from many parts of the world. It is, however, worrying that there will be parts of the globe, where this tracking of variants does not occur. As we don't want any more surprises, it would be a good idea to increase the number and geographical distribution of PCR labs.