It is in the nature of viruses to mutate. Often these die out but sometimes a mutated version will become the predominant variant in a population. New strains become more common by being in the right place at the right time. (Flu viruses behave in the same way, which is why flu vaccines are tweaked each year.) Vaccines train the immune system to attack several parts of the virus, so even though the spike has mutated, the vaccines should still work. Should we get to the stage where vaccines need to be regularly updated, the ones we have are very easy to tweak.
- The virus that was first detected in Wuhan, China, is not the same one you will find in most corners of the world. It probably spread at low levels initially, only being noticed when a serious outbreak of cases occurred.
- By this time it is thought that it was already spreading outside China, maybe as early as September 2019 in Italy, and later that autumn in France, Brazil and the US. This strain was different to the original Chinese strain and became the dominant strain as it spread world-wide.
- The D614G mutation emerged in Europe in Feb. 2020 and became the globally dominant form of the virus.
- Another, called A222V, spread across Europe and was linked to people's summer holidays in Spain.
- The Alpha variant first detected in London UK in September 2020. (A similar strain was circulating in Italy as early as August 2020, before the first known cases in England. )
- The Beta variant emerged in South Africa.
- The Gamma variant was found in Brazil in Nov. 2020.
- The Delta variant was found emerged in India in Oct. 2020.
- Variant 20C-US (identified in Jan. 2021) now accounts for almost 50% of new cases in the US.
- A Nigerian variant (P681H) has a number of gene changes.
- Variant Omicron emerged in Botswana (reported on 24 Nov. 2021). It has an unusually large number of mutations which make it more transmissible, and is now present in many countries. So far cases are mild and few require hospitalisation. Symptoms are more like a common cold.
Covid-19 variants (mutations) are labelled in several ways.
Media reports typically refer to the country where the new variant has first been identified. For example, the Brazilian, South African or UK variants. However, this does not necessarily reflect the country where the mutation first occurred, as it may have spread to other countries before being identified. Some countries (e.g. UK) are doing more testing to identify mutations than others.
- A new variant may initially be referenced by noting the area of the genetic sequence where the mutation occurred. For example, the D614G mutation.
- 20B.1.1.248: A variant with 12 mutations (including N501Y and E484E) identified in Brazil.
- 20B.1.1.7.: A faster spreading variant spreading identified in the UK in late 2020 and early 2021.
- 20C-US: A variant found in the US.
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