Open Access Open Access  Restricted Access Subscription or Fee Access

SARS-CoV-2 B.1.617.2 (Delta), B.1.617.2.1 (Delta Plus) Variant and Vaccine Strategies

Chandani Chandani Kamble, Vikas Kamble, Prakash Kamble


In India and other countries throughout the world, the Delta (B.1.617.2) variety has major devastation. First spotted in October 2020, it has already spread to more than 100 nations, prompting WHO to declare it as a worldwide variant of concern (VOC). Sub-lineages of the original B.1.617 variant include Delta (B.1.617.2), Delta plus (B.1.617.2.1), and Kappa (B.1.617.1). Vaccine deployment, safe-distancing, and timely lockdowns significantly reduced COVID-19 hospitalizations and deaths before the implementation of B.1.617. The Delta variant, which is said to be more contagious and for which existing vaccines appear to be ineffective, has sparked a recurrence of cases. As a result, there is a pressing need for better B.1.617 variant surveillance. While the Delta variant is gradually outpacing the Beta variant in terms of distribution, the Beta variant spread remains a concern due to its vaccine resistance.


SARS-CoV-2, COVID-19, variants, vaccines, spike protein, variants of concern (VOC)

Full Text:



Zoumpourlis, V., Goulielmaki, M., Rizos, E., Baliou, S., Spandidos, D.A., 2020. [Comment] The COVID-19 pandemic as a scientific and social challenge in the 21st century. Mol. Med. Rep. 22(4):3035–3048.

Lauring, A.S., Hodcroft, E.B., 2021. Genetic Variants of SARS-CoV-2—What Do They Mean? JAMA 325(6):529–531.

CDC, 2021. SARS-CoV-2 Variant Classifications and Definitions [WWW Document]. URL (accessed 7.9.21).

PHE, 2021. SARS-CoV-2 variants of concern and variants under investigation in England [WWW Document].URL


Mahase, E., 2021. Delta variant: What is happening with transmission, hospital admissions, and restrictions? BMJ 373, n1513.

Lustig, Y., Zuckerman, N., Nemet, I., Atari, N., Kliker, L., Regev-Yochay, G., Sapir, E., Mor, O., Alroy-Preis, S., Mendelson, E., Mandelboim, M., 2021. Neutralising capacity against Delta (B.1.617.2) and other variants of concern following Comirnaty (BNT162b2, BioNTech/Pfizer) vaccination in health care workers, Israel. Euro Surveill. 2021 Jul;26(26):2100557.

Bernal, J.L., Andrews, N., Gower, C., Gallagher, E., Simmons, R., Thelwall, S., Stowe, J., Tessier, E., Groves, N., Dabrera, G., Myers, R., Campbell, C., Amirthalingam, G., Edmunds, M., Zambon, M., Brown, K., Hopkins, S., Chand, M., Ramsay, M., 2021. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. medRxiv 2021.05.22.21257658.

Planas, D., Bruel, T., Grzelak, L., Guivel-Benhassine, F., Staropoli, I., Porrot, F., Planchais, C., Buchrieser, J., Rajah, M.M., Bishop, E., Albert, M., Donati, F., Prot, M., Behillil, S., Enouf, V., Maquart, M., Smati-Lafarge, M., Varon, E., Schortgen, F., Yahyaoui, L., Gonzalez, M., De Sèze, J., Péré, H., Veyer, D., Sève, A., Simon-Lorière, E., Fafi-Kremer, S., Stefic, K., Mouquet, H., Hocqueloux, L., van der Werf, S., Prazuck, T., Schwartz, O., 2021a. Sensitivity of infectious SARS-CoV-2 B.1.1.7 and B.1.351 variants to neutralizing antibodies. Nat. Med. 27, 917–924.

Dagan, N.; Barda, N.; Kepten, E.; Miron, O.; Perchik, S.; Katz, M.A.; Hernan, M.A.; Lipsitch, M.; Reis, B.; Balicer, R.D. Bnt162b2mrna covid-19 vaccine in a nationwide mass vaccination setting. N. Engl. J. Med. 2021, 384, 1412–1423.

Starr, T.N.; Greaney, A.J.; Addetia, A.; Hannon, W.W.; Choudhary, M.C.; Dingens, A.S.; Li, J.Z.; Bloom, J.D. Prospective mapping of viral mutations that escape antibodies used to treat covid-19. Science 2021:371(6531):850–854.

Deng, X.; Garcia-Knight, M.A.; Khalid, M.M.; Servellita, V.;Wang, C.; Morris, M.K.; Sotomayor-Gonzalez, A.; Glasner, D.R.; Reyes, K.R.; Gliwa, A.S.; et al. Transmission, infectivity, and neutralization of a spike l452r sars-cov-2 variant. Cell 2021:184(13)3426–3437.

Fehr, A.R.; Perlman, S. Coronaviruses: An overview of their replication and pathogenesis. Methods Mol. Biol. 2015, 1282, 1–23.

Zhang, W.; Davis, B.D.; Chen, S.S.; Sincuir Martinez, J.M.; Plummer, J.T.; Vail, E. Emergence of a novel sars-cov-2 variant in southern california. JAMA 2021:325(13):1324–1326.

Rosa-Aquino, C.D.a.P. What we know about the dangerous covid b.1.617.2 (delta) variant. N. Y. Intell. 2021.

Susan Jacob, et al. Impact of societal restrictions and lockdown on trauma admissions during the COVID-19 pandemic: a single-centre cross-sectional observational study. ANZ J Surg. 2020 Nov;90(11):2227-2231.

Wall, E.C.;Wu, M.; Harvey, R.; Kelly, G.;Warchal, S.; Sawyer, C.; Daniels, R.; Hobson, P.; Hatipoglu, E.; Ngai, Y.; et al. Neutralising antibody activity against sars-cov-2 vocs b.1.617.2 and b.1.351 by bnt162b2 vaccination. Lancet 2021, 397 (10292):2331–2333.

Yeung, J. There Are at Least 200 Known Cases of the Delta Plus Coronavirus Variant Worldwide. Here’s What We Know. CNN: 2021. Available online: (accessed on 29 June 2021).

Bernd Jahrsdörfer, et al. BNT162b2 Vaccination Elicits Strong Serological Immune Responses Against SARS-CoV-2 Including Variants of Concern in Elderly Convalescents. Front Immunol. 2021 Sep 29;12:743422.

Abdool Karim, S.S.; de Oliveira, T. New sars-cov-2 variants—clinical, public health, and vaccine implications. N. Engl. J. Med. 2021, 384(19)1866–1868.

Lacobucci, G. Covid-19: Single vaccine dose is 33% effective against variant from India, data show. BMJ 2021, 373, n1346.

England, P.H. Effectiveness of Covid-19 Vaccines on Hospitalisation Disease with the Delta Variant. 2021. Available online: (accessed on 20 May 2021).

Sabino, E.C.; Buss, L.F.; Carvalho, M.P.S.; Prete, C.A., Jr.; Crispim, M.A.E.; Fraiji, N.A.; Pereira, R.H.M.; Parag, K.V.; da Silva Peixoto, P.; Kraemer, M.U.G.; et al. Resurgence of covid-19 in manaus, brazil, despite high seroprevalence. Lancet 2021, 397 (10273):452–455.

Faria, N.R.; Mellan, T.A.; Whittaker, C.; Claro, I.M.; Candido, D.D.S.; Mishra, S.; Crispim, M.A.E.; Sales, F.C.S.; Hawryluk, I.; McCrone, J.T.; et al. Genomics and epidemiology of the p.1 sars-cov-2 lineage in manaus, brazil. Science 2021, 372 (6544):815–821.

Naveca, F.G.; Nascimento, V.; de Souza, V.C.; Corado, A.L.; Nascimento, F.; Silva, G.; Costa, A.; Duarte, D.; Pessoa, K.; Mejia, M.; et al. Covid-19 in amazonas, brazil, was driven by the persistence of endemic lineages and p.1 emergence. Nat. Med. 2021.

de Souza, W.M.; Amorim, M.R.; Sesti-Costa, R.; Coimbra, L.D.; de Toledo-Teixeira, D.A.; Parise, P.L.; Barbosa, P.P.; Bispo-dos- Santos, K.; Mofatto, L.S.; Simeoni, C.L.; et al. Levels of sars-cov-2 lineage p.1 neutralization by antibodies elicited after natural infection and vaccination. Lancet 2021: 2(10)E527-E535, OCTOBER 01, 2021

Takuya Tada, H.Z.; Dcosta, B.M.; Samanovic, M.I.; Mulligan, M.J.; Landau, N.R. The spike proteins of sars-cov-2 b.1.617 and b.1.618 variants identified in India provide partial resistance to vaccine-elicited and therapeutic monoclonal antibodies. bioRxiv 2021.

Liu, W.; Xie, Y.; Ma, J.; Luo, X.; Nie, P.; Zuo, Z.; Lahrmann, U.; Zhao, Q.; Zheng, Y.; Zhao, Y.; et al. Ibs: An illustrator for the presentation and visualization of biological sequences. Bioinformatics Bioinformatics. 2015 Oct 15;31(20):3359-61.

Minseo Jeong, Delta plus variant of SARS-CoV-2: How does it compare with the delta variant?, Medical News Today, 2021 July 6.

SARS-CoV-2 variant classifications and definitions. (July 16, 2021).

Kannan S.R., Spratt A.N., Quinn T.P., Heng X., Lorson C.L., Sonnerborg A., Byrareddy S.N., Singh K. Infectivity of SARS-CoV-2: there is something more than D614G? J. Neuroimmune Pharmacol. 2020;15(4):574–577. [PMC free article] [PubMed] [Google Scholar]

Spratt A.N., Kannan S.R., Woods L.T., Weisman G.A., Quinn T.P., Lorson C.L., Sonnerborg A., Byrareddy S.N., Singh K. Evolution, correlation, structural impact and dynamics of emerging SARS-CoV-2 variants. Comput. Struct. Biotechnol. J. 2021; 19: 3799–3809. [PMC free article] [PubMed] [Google Scholar]

Kannan, S. R., Spratt, A. N., Cohen, A. R., Naqvi, S. H., Chand, H. S., Quinn, T. P., Lorson, C. L., Byrareddy, S. N., & Singh, K. (2021). Evolutionary analysis of the Delta and Delta Plus variants of the SARS-CoV-2 viruses. Journal of autoimmunity, 124, 102715. Advance online publication.

Amanat, F.; Krammer, F. Sars-cov-2 vaccines: Status report. Immunity 2020, 52(4):583–589.

Grifoni, A.; Weiskopf, D.; Ramirez, S.I.; Mateus, J.; Dan, J.M.; Moderbacher, C.R.; Rawlings, S.A.; Sutherland, A.; Premkumar, L.; Jadi, R.S.; et al. Targets of t cell responses to sars-cov-2 coronavirus in humans with covid-19 disease and unexposed individuals. Cell 2020, 181(7):1489–1501.

Bisht, H.; Roberts, A.; Vogel, L.; Bukreyev, A.; Collins, P.L.; Murphy, B.R.; Subbarao, K.; Moss, B. Severe acute respiratory syndrome coronavirus spike protein expressed by attenuated vaccinia virus protectively immunizes mice. Proc. Natl. Acad. Sci.USA 2004, 101(17), 6641–6646.

WHO. Draft Landscape and Tracker of Covid-19 Candidate Vaccines. 2021. Available online: (accessed on 26 May 2021).

Merlin, M.; Gecchele, E.; Capaldi, S.; Pezzotti, M.; Avesani, L. Comparative evaluation of recombinant protein production in different biofactories: The green perspective. BioMed Res. Int. 2014, 2014, 136419.

Keech, C.; Albert, G.; Cho, I.; Robertson, A.; Reed, P.; Neal, S.; Plested, J.S.; Zhu, M.; Cloney-Clark, S.; Zhou, H.; et al. Phase 1-2 trial of a sars-cov-2 recombinant spike protein nanoparticle vaccine. N. Engl. J. Med. 2020, 383, 2320–2332.

Novavax. Novavax Confirms High Levels of Efficacy against Original and Variant Covid-19 Strains in United Kingdom and South Africa Trials. CISION 2021. Available online: (accessed on 20 May 2021).

Folegatti, P.M.; Ewer, K.J.; Aley, P.K.; Angus, B.; Becker, S.; Belij-Rammerstorfer, S.; Bellamy, D.; Bibi, S.; Bittaye, M.; Clutterbuck, E.A.; et al. Safety and immunogenicity of the chadox1 ncov-19 vaccine against sars-cov-2: A preliminary report of a phase 1/2, single-blind, randomised controlled trial. Lancet 2020, 396 (10249):467–478.

Jackson, L.A.; Anderson, E.J.; Rouphael, N.G.; Roberts, P.C.; Makhene, M.; Coler, R.N.; McCullough, M.P.; Chappell, J.D. Denison, M.R.; Stevens, L.J.; et al. An mrna vaccine against sars-cov-2—Preliminary report. N. Engl. J. Med. 2020, 383, 1920–1931.

Walsh, E.E.; Frenck, R.; Falsey, A.R.; Kitchin, N.; Absalon, J.; Gurtman, A.; Lockhart, S.; Neuzil, K.; Mulligan, M.J.; Bailey, R.; et al. Rna-based covid-19 vaccine bnt162b2 selected for a pivotal efficacy study. medRxiv. Preprint. 2020 Aug 20 [revised 2020 Aug 28]

Yan, Z.P.; Yang, M.; Lai, C.L. Covid-19 vaccines: A review of the safety and efficacy of current clinical trials. Pharmaceuticals 2021, 14(5):406.

Machhi, J.; Shahjin, F.; Das, S.; Patel, M.; Abdelmoaty, M.M.; Cohen, J.D.; Singh, P.A.; Baldi, A.; Bajwa, N.; Kumar, R.; et al. Nanocarrier vaccines for sars-cov-2. Adv. Drug Deliv. Rev. 2021, 171, 215–239.

Biospace. Covaxx’s Covid-19 Vaccine, Ub-612, Induced Neutralizing Antibodies in 100% of Participants during Phase 1 Clinical Trial. 2021. Available online: (accessed on 20 May 2021).

King, A. Protein-Based Covid-19 Vaccines Could Overshadow Rivals. 2020. Available online: (accessed on 20 May 2021).

Li, Y.R.T.; Smoot, J.; Liu, C.; Watkins, S.; Zhou, O. A comprehensive review of the global efforts on covid-19 vaccine development. ACS Cent. Sci. 2021:7(4):512–533.

Bonam, S.R.; Partidos, C.D.; Halmuthur, S.K.M.; Muller, S. An overview of novel adjuvants designed for improving vaccine efficacy. Trends Pharm. Sci. 2017, 38(9):771–793.

Amanat, F.; Stadlbauer, D.; Strohmeier, S.; Nguyen, T.H.O.; Chromikova, V.; McMahon, M.; Jiang, K.; Arunkumar, G.A.; Jurczyszak, D.; Polanco, J.; et al. A serological assay to detect sars-cov-2 seroconversion in humans. Nat. Med. 2020, 26(7):1033–1036.

Hotez, P.J.; Corry, D.B.; Bottazzi, M.E. Covid-19 vaccine design: The janus face of immune enhancement. Nat. Rev. Immunol. 2020, 20(6):347–348.

Krammer, F. Sars-cov-2 vaccines in development. Nature 2020, 586, 516–527.

Syomin, B.V.; Ilyin, Y.V. Virus-like particles as an instrument of vaccine production. Mol. Biol. 2019, 53(3):367–379.

Kushnir, N.; Streatfield, S.J.; Yusibov, V. Virus-like particles as a highly efficient vaccine platform: Diversity of targets and production systems and advances in clinical development. Vaccine 2012, 31(1):58–83.

Corbett, K.S.; Edwards, D.K.; Leist, S.R.; Abiona, O.M.; Boyoglu-Barnum, S.; Gillespie, R.A.; Himansu, S.; Schafer, A.; Ziwawo, C.T.; DiPiazza, A.T.; et al. Sars-cov-2 mrna vaccine design enabled by prototype pathogen preparedness. Nature 2020, 586 (7830):567–571.

Ulmer, J.B.; Geall, A.J. Recent innovations in mrna vaccines. Curr. Opin. Immunol. 2016, 41,


Cohen, J. ‘Absolutely Remarkable’: No One Who Got Moderna’s Vaccine in Trial Developed Severe Covid-19. 30 November 2020. Available online:

absolutely-remarkable-no-one-who-got-modernas-vaccine-trial-developed-severe-covid-19 (accessed on 20 May 2021).

Kamar, N.; Abravanel, F.; Marion, O.; Couat, C.; Izopet, J.; Del Bello, A. Three doses of an mrna covid-19 vaccine in solid-organ transplant recipients. N Engl J Med. 2021 Aug 12;385(7):


Callaway, E. Mix-and-match covid vaccines trigger potent immune response. Nature. 2021 May;593(7860):491.

Kremsner, P.; Mann, P.; Bosch, J.; Fendel, R.; Gabor, J.J.; Kreidenweiss, A.; Kroidl, A.; Leroux-Roels, I.; Leroux-Roels, G.; Schindler, C.; et al. Phase 1 assessment of the safety and immunogenicity of an mrna- lipid nanoparticle vaccine candidate against sars-cov-in human volunteers. Wien Klin Wochenschr. 2021; 133(17-18): 931–941.

Curevac’s Covid-19 Vaccine Candidate, Cvncov, Suitable for Standard Fridge Temperature Logistics. 2020. Available online: (accessed on 26 May 2021).

Dolgin, E. Curevac covid vaccine let-down spotlights mrna design challenges. 2021 Jun; 594(7864):483.

Silveira, M.M.; Oliveira, T.L.; Schuch, R.A.; McBride, A.J.A.; Dellagostin, O.A.; Hartwig, D.D. DNA vaccines against leptospirosis: A literature review. Vaccine. 2017 Oct 9; 35(42):5559-5567.

Izda, V.; Jeffries, M.A.; Sawalha, A.H. Covid-19: A review of therapeutic strategies and vaccine candidates. Clin. Immunol. 2021, 222, 108634.

Zhu, F.C.; Guan, X.H.; Li, Y.H.; Huang, J.Y.; Jiang, T.; Hou, L.H.; Li, J.X.; Yang, B.F.;Wang, L.;Wang,W.J.; et al. Immunogenicity and safety of a recombinant adenovirus type-5-vectored covid-19 vaccine in healthy adults aged 18 years or older: A randomised, double-blind, placebo-controlled, phase 2 trial. Lancet 2020, 395(10240):1845-1854.

Van Doremalen, N.; Lambe, T.; Spencer, A.; Belij-Rammerstorfer, S.; Purushotham, J.N.; Port, J.R.; Avanzato, V.A.; Bushmaker, T.; Flaxman, A.; Ulaszewska, M.; et al. Chadox1 ncov-19 vaccine prevents sars-cov-2 pneumonia in rhesus macaques. Nature 2020,; 586(7830):578-582.

Ewer, K.J.; Barrett, J.R.; Belij-Rammerstorfer, S.; Sharpe, H.; Makinson, R.; Morter, R.; Flaxman, A.; Wright, D.; Bellamy, D.; Bittaye, M.; et al. T cell and antibody responses induced by a single dose of chadox1 ncov-19 (azd1222) vaccine in a phase 1/2 clinical trial. Nat. Med. 2021, 27(2):270–278.

Voysey, M.; Clemens, S.A.C.; Madhi, S.A.;Weckx, L.Y.; Folegatti, P.M.; Aley, P.K.; Angus, B.; Baillie, V.L.; Barnabas, S.L.; Bhorat, Q.E.; et al. Safety and efficacy of the chadox1 ncov-19 vaccine (azd1222) against sars-cov-2: An interim analysis of four randomized controlled trials in brazil, south africa, and the uk. Lancet 2021, 397, 99–111.

JOhnson & Johnson Announces Single-Shot Janssen Covid-19 Vaccine Candidate Met Primary Endpoints in Interim Analysis of Its Phase 3 Ensemble Trial. 2021. Available online: (accessed on 26 May 2021).

Kowarz, E.L.K.; Reis, J.; Bracharz, S.; Kochanek, S.; Marschalek, R. Vaccine-induced covid-19 mimicry” syndrome:Splice reactions within the sars-cov-2 spike open reading frame result in spike protein variants that may cause thromboembolic events in patients immunized with vector-based vaccines. Res. Sq. 2021. [CrossRef]

Logunov, D.Y.; Dolzhikova, I.V.; Shcheblyakov, D.V.; Tukhvatulin, A.I.; Zubkova, O.V.; Dzharullaeva, A.S.; Kovyrshina, A.V.; Lubenets, N.L.; Grousova, D.M.; Erokhova, A.S.; et al. Safety and efficacy of an rad26 and rad5 vector-based heterologous primeboost covid-19 vaccine: An interim analysis of a randomised controlled phase 3 trial in russia. Lancet 2021, 397, 671–681.

Smith, T.R.F.; Patel, A.; Ramos, S.; Elwood, D.; Zhu, X.; Yan, J.; Gary, E.N.; Walker, S.N.; Schultheis, K.; Purwar, M.; et al. Immunogenicity of a DNA vaccine candidate for covid-19. Nat. Commun. 2020, 11(1):2601.



  • There are currently no refbacks.

Copyright (c) 2021 Research & Reviews: Journal of Medical Science and Technology

This Journal archive has been shifted to: