Virus evolution

Humanity has suffered from many pandemics in the past, but the SARS-Cov-2 virus is the first to have its genome studied so extensively while the pandemic is ongoing. In a previous blog I looked at how the Delta variant displaced all other variants in the UK due to its increased infectiousness. Unfortunately, the increased infectiousness of Delta was not accompanied by reduced deadliness.

As bad luck would have it, the recent Omicron variant of SARS-Cov-2 is even more infectious, and displaced all other variants in the UK in record time; see Figure 1.

Figure 1. Proportion of SARS-Cov-2 variants in England over time. Source: Own calculations using data from Wellcome-Sanger Institute to 5th February 2022 and the variant-classification system from the World Health Organisation.

Figure 1 shows evolution in real time when a new genetic variant is fitter for its environment, it spreads rapidly, as shown in Table 1:

Table 1. Time taken to account for 95% of COVID-19 cases in England. Selected variants. Source: Own calculations using data from Wellcome-Sanger Institute to 5th February 2022 and the variant-classification system from the World Health Organisation.

VariantTime taken
Alpha 5 months
Delta 84 days
Omicron 35 days

Evolution never stops, as new sub-lineages of Omicron have already been genetically identified. We're going to have to learn to live with SARS-Cov-2.

 

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Stephen Richards
Stephen Richards is the Managing Director of Longevitas