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.
| Variant | Time 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.
Previous posts
Claims and Consequences
This blog discusses misinformation - including deliberate disinformation - during the SARS-COV-2 pandemic. I won't link directly to anti-vaccine content to avoid adding search-engine credibility to material best left unfound.
Measles - a short history lesson
The UK Health Security Agency recently issued a press release, warning that too few children were vaccinated against measles. With the benefits of vaccination and a developed healthcare system, it is easy to forget that measles was often a fatal disease for young children. Table 1 shows just how deadly measles was at the start of last century without vaccination:
Add new comment