SARS-CoV-2 Delta variant
a subvariant of lineage B.1.617
The Delta variant (B.1.617.2) was a variant of SARS-CoV-2, the virus that causes COVID-19. It was first detected in India on 5 October 2020. The Delta variant was named on 31 May 2021 and had spread to over 179 countries by 22 November 2021. The World Health Organization (WHO) indicated in June 2021 that the Delta variant was becoming the dominant strain globally.
It has mutations in the gene encoding the SARS-CoV-2 spike protein causing the substitutions T478K, P681R and L452R, which are known to affect transmissibility of the virus as well as whether it can be neutralised by antibodies for previously circulating variants of the COVID-19 virus. In August 2021, Public Health England (PHE) reported secondary attack rate in household contacts of non-travel or unknown cases for Delta to be 10.8% vis-à-vis 10.2% for the Alpha variant; the case fatality rate for those 386,835 people with Delta is 0.3%, where 46% of the cases and 6% of the deaths are unvaccinated and below 50 years old. Immunity from previous recovery or COVID-19 vaccines are effective in preventing severe disease or hospitalisation from infection with the variant.
On 7 May 2021, PHE changed their classification of lineage B.1.617.2 from a variant under investigation (VUI) to a variant of concern (VOC) based on an assessment of transmissibility being at least equivalent to B.1.1.7 (Alpha variant); the UK's SAGE using May data estimated a "realistic" possibility of being 50% more transmissible. On 11 May 2021, the WHO also classified this lineage VOC, and said that it showed evidence of higher transmissibility and reduced neutralisation. On 15 June 2021, the Centers for Disease Control and Prevention (CDC) declared Delta a variant of concern.
This brief starts where responsible research should: with the source description of “SARS-CoV-2 Delta variant” as a subvariant of lineage B.1.617. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as a subvariant of lineage B.1.617. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 11, 2026. The linked authority identifier is Q107055182. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2020 and 2021.
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This entry incorporates text from “SARS-CoV-2 Delta variant” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.