Delta variant (B.1.617.2) of SARS-CoV-2: Mutations, impact, challenges and possible solutions

Hum Vaccin Immunother. 2022 Nov 30;18(5):2068883. doi: 10.1080/21645515.2022.2068883. Epub 2022 May 4.


Since commencement of COVID-19 pandemic, several SARS-CoV-2 variants have emerged amid containment efforts via vaccination. The Delta variant (B.1.617.2), discovered in October 2020, was designated as a VOC by the WHO on May 11, 2021. The enhanced transmissibility of Delta variant has been associated with critical mutations such as D614G, L452R, P681R, and T478K in the S-protein. The increased affinity of the S-protein and ACE2 has been postulated as a key reason for decreased vaccine efficacy. As per evidence, the Delta variant possesses increased transmissibility and decreased vaccine efficacy compared to other VOCs like Alpha and Beta. This has led to concerns regarding the acquisition of novel mutations in the Delta variant and outbreaks in vulnerable communities, including vaccinated people. In this mini-review of Delta variant, we have explained its evolution and characteristics, the impact of spike mutations on infectivity and immune evasion, and measures to combat future outbreaks.

Keywords: COVID-19; Delta variant; Omicron variant; SARS-CoV-2; spike mutations; vaccination.

Publication types

  • Review

MeSH terms

  • Angiotensin-Converting Enzyme 2
  • COVID-19* / prevention & control
  • Humans
  • Membrane Glycoproteins
  • Mutation
  • Pandemics
  • Peptidyl-Dipeptidase A
  • SARS-CoV-2* / genetics
  • Spike Glycoprotein, Coronavirus / genetics
  • Viral Envelope Proteins


  • Membrane Glycoproteins
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • spike protein, SARS-CoV-2
  • Peptidyl-Dipeptidase A
  • Angiotensin-Converting Enzyme 2

Supplementary concepts

  • SARS-CoV-2 variants

Grant support

The author(s) reported there is no funding associated with the work featured in this article.