Skip to main content
Download PDF

A Comprehensive Review of COVID-19 Virology, Vaccines, Variants, and Therapeutics

Current Medical Science volume 41, pages 1037–1051 (2021)Cite this article

Summary

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen of the coronavirus disease 2019 (COVID-19), has caused more than 179 million infections and 3.8 million deaths worldwide. Throughout the past year, multiple vaccines have already been developed and used, while some others are in the process of being developed. However, the emergence of new mutant strains of SARS-CoV-2 that have demonstrated immune-evading characteristics and an increase in infective capabilities leads to potential ineffectiveness of the vaccines against these variants. The purpose of this review article is to highlight the current understanding of the immunological mechanisms of the virus and vaccines, as well as to investigate some key variants and mutations of the virus driving the current pandemic and their impacts on current management guidelines. We also discussed new technologies being developed for the prevention, treatment, and detection of SARS-CoV-2. In this paper, we thoroughly reviewed and provided crucial information on SARS-CoV-2 virology, vaccines and drugs being used and developed for its prevention and treatment, as well as important variant strains. Our review paper will be beneficial to health care professionals and researchers so they can have a better understanding of the basic sciences, prevention, and clinical treatment of COVID-19 during the pandemic. This paper consists of the most updated information that has been available as of June 21, 2021.

References

  1. Rothan HA, Byrareddy SN. The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak. J Autoimmun, 2020,109:102433

    CAS  PubMed  PubMed Central  Google Scholar 

  2. Hatmal MM, Alshaer W, Al-Hatamleh MAI, et al. Comprehensive Structural and Molecular Comparison of Spike Proteins of SARS-CoV-2, SARS-CoV and MERS-CoV, and Their Interactions with ACE2. Cells, 2020,9(12):2638

    CAS  PubMed Central  Google Scholar 

  3. Masters PS. Coronavirus genomic RNA packaging. Virology, 2019,537:198–207

    CAS  PubMed  Google Scholar 

  4. Kaur N, Singh R, Dar Z, et al. Genetic comparison among various coronavirus strains for the identification of potential vaccine targets of SARS-CoV2. Infect Genet Evol, 2021,89:104490

    CAS  PubMed  Google Scholar 

  5. Zhou P, Yang XL, Wang XG, et al. A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature, 2020,579(7798):270–273

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Bai C, Warshel A. Critical Differences between the Binding Features of the Spike Proteins of SARS-CoV-2 and SARS-CoV. J Phys Chem B, 2020,124(28):5907–5912

    CAS  PubMed  Google Scholar 

  7. Huang Y, Yang C, Xu XF, et al. Structural and functional properties of SARS-CoV-2 spike protein: potential antivirus drug development for COVID-19. Acta Pharmacol Sin, 2020,41(9):1141–1149

    PubMed  PubMed Central  Google Scholar 

  8. Ozono S, Zhang Y, Ode H, et al. SARS-CoV-2 D614G spike mutation increases entry efficiency with enhanced ACE2-binding affinity. Nat Commun, 2021,12(1):848

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Rahman N, Basharat Z, Yousuf M, et al. Virtual Screening of Natural Products against Type II Transmembrane Serine Protease (TMPRSS2), the Priming Agent of Coronavirus 2 (SARS-CoV-2). Molecules, 2020,25(10):2271

    CAS  PubMed Central  Google Scholar 

  10. Hoffmann M, Kleine-Weber H, Schroeder S, et al. SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor. Cell, 2020,181(2):271–80.e8

    CAS  PubMed  PubMed Central  Google Scholar 

  11. Zhou Z, Zhao N, Shu Y, et al. Effect of Gastrointestinal Symptoms in Patients With COVID-19. Gastroenterology, 2020,158(8):2294–2297

    CAS  PubMed  Google Scholar 

  12. Perisetti A, Goyal H, Gajendran M, et al. Prevalence, Mechanisms, and Implications of Gastrointestinal Symptoms in COVID-19. Front Med, 2020,7:588711

    Google Scholar 

  13. O’Hearn M, Liu J, Cudhea F, et al. Coronavirus Disease 2019 Hospitalizations Attributable to Cardiometabolic Conditions in the United States: A Comparative Risk Assessment Analysis. J Am Heart Assoc, 2021,10(5): e019259

    PubMed  PubMed Central  Google Scholar 

  14. Caramelo F, Ferreira N, Oliveiros B. Estimation of risk factors for COVID-19 mortality— preliminary results. medRxiv, 2020,02.24.20027268

  15. Gheblawi M, Wang K, Viveiros A, et al. Angiotensin-Converting Enzyme 2: SARS-CoV-2 Receptor and Regulator of the Renin-Angiotensin System: Celebrating the 20th Anniversary of the Discovery of ACE2. Circ Res, 2020,126(10):1456–1474

    CAS  PubMed  Google Scholar 

  16. Coperchini F, Chiovato L, Croce L, et al. The cytokine storm in COVID-19: An overview of the involvement of the chemokine/chemokine-receptor system. Cytokine Growth Factor Rev, 2020,53:25-32

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Faqihi F, Alharthy A, Memish ZA, et al. Comment on Hu et al: The cytokine storm and COVID-19. J Med Virol, 2021,93(2):631–633

    CAS  PubMed  Google Scholar 

  18. Biswas S, Thakur V, Kaur P, et al. Blood clots in COVID-19 patients: Simplifying the curious mystery. Med Hypotheses, 2021,146:110371

    CAS  PubMed  Google Scholar 

  19. Huang Q, Wu X, Zheng X, et al. Targeting inflammation and cytokine storm in COVID-19. Pharmacol Res, 2020,159:105051

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Tay MZ, Poh CM, Rénia L, et al. The trinity of COVID-19: immunity, inflammation and intervention. Nat Rev Immunol, 2020,20(6):363–374

    CAS  PubMed  Google Scholar 

  21. Zheng HY, Zhang M, Yang CX, et al. Elevated exhaustion levels and reduced functional diversity of T cells in peripheral blood may predict severe progression in COVID-19 patients. Cell Mol Immunol, 2020,17(5):541–543

    CAS  PubMed  PubMed Central  Google Scholar 

  22. Chowdhury MA, Hossain N, Kashem MA, et al. Immune response in COVID-19: A review. J Infect Public Health, 2020,13(11):1619–1629

    PubMed  PubMed Central  Google Scholar 

  23. Lee WS, Wheatley AK, Kent SJ, et al. Antibody-dependent enhancement and SARS-CoV-2 vaccines and therapies. Nat Microbiol, 2020,5(10):1185–1191

    PubMed  Google Scholar 

  24. Tirado SM, Yoon KJ. Antibody-dependent enhancement of virus infection and disease. Viral Immunol, 2003,16(1):69–86

    CAS  PubMed  Google Scholar 

  25. Ricke DO. Two Different Antibody-Dependent Enhancement (ADE) Risks for SARS-CoV-2 Antibodies. Front Immunol, 2021,12:640093

    CAS  PubMed  PubMed Central  Google Scholar 

  26. Huang Q, Zeng J, Yan J. COVID-19 mRNA vaccines. J Genet Genomics, 2021,48(2):107–114

    PubMed  PubMed Central  Google Scholar 

  27. Livingston EH, Malani PN, Creech CB. The Johnson & Johnson Vaccine for COVID-19. JAMA, 2021,325(15): 1575

    CAS  PubMed  Google Scholar 

  28. Al Kaabi N, Zhang Y, Xia S, et al. Effect of 2 Inactivated SARS-CoV-2 Vaccines on Symptomatic COVID-19 Infection in Adults: A Randomized Clinical Trial. JAMA, 2021, e218565. doi: https://doi.org/10.1001/jama.2021.8565. Epub ahead of prrnt. PMID: 34037666; PMCID: PMC8156175.

  29. Xia S, Zhang Y, Wang Y, et al. Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBIBP-CorV: a randomised, double-blind, placebo-controlled, phase 1/2 trial. Lancet Infect Dis, 2021,21(1):39–51

    CAS  PubMed  Google Scholar 

  30. Wu Z, Hu Y, Xu M, et al. Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine (CoronaVac) in healthy adults aged 60 years and older: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial. Lancet Infect Dis, 2021,21(6):803–812

    CAS  PubMed  PubMed Central  Google Scholar 

  31. Xu S, Yang K, Li R, et al. mRNA Vaccine Era-Mechanisms, Drug Platform and Clinical Prospection. Int J Mol Sci, 2020,21(18):6582

    CAS  Google Scholar 

  32. Cagigi A, Loré K. Immune Responses Induced by mRNA Vaccination in Mice, Monkeys and Humans. Vaccines, 2021,9(1):61

    CAS  PubMed  PubMed Central  Google Scholar 

  33. Linares-Fernández S, Lacroix C, Exposito JY, et al. Tailoring mRNA Vaccine to Balance Innate/Adaptive Immune Response. Trends Mol Med, 2020,26(3):311–323

    PubMed  Google Scholar 

  34. Schoenmaker L, Witzigmann D, Kulkarni JA, et al. mRNA-lipid nanoparticle COVID-19 vaccines: Structure and stability. Int J Pharm, 2021,601:120586

    CAS  PubMed  PubMed Central  Google Scholar 

  35. Dyer O. Covid-19: EMA defends AstraZeneca vaccine as Germany and Canada halt rollouts. BMJ, 2021,373: n883

    PubMed  Google Scholar 

  36. Xia S, Duan K, Zhang Y, et al. Effect of an Inactivated Vaccine Against SARS-CoV-2 on Safety and Immunogenicity Outcomes: Interim Analysis of 2 Randomized Clinical Trials. JAMA, 2020,324(10):951–960

    CAS  PubMed  Google Scholar 

  37. Zhang Y, Zeng G, Pan H, et al. Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine in healthy adults aged 18–59 years: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial. Lancet Infect Dis, 2021,21(2):181–192

    CAS  PubMed  Google Scholar 

  38. Golob JL, Lugogo N, Lauring AS, et al. SARS-CoV-2 vaccines: a triumph of science and collaboration. JCI Insight, 2021,6(9):149187

    PubMed  Google Scholar 

  39. Zhu FC, Li YH, Guan XH, et al. Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial. Lancet, 2020,395(10240):1845–1854

    CAS  PubMed  PubMed Central  Google Scholar 

  40. Mallapaty S. China’s COVID vaccines are going globalbut questions remain. Nature, 2021,593(7858):178–179

    CAS  PubMed  Google Scholar 

  41. Logunov DY, Dolzhikova IV, Shcheblyakov DV, et al. Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia. Lancet, 2021,397(10275):671–681

    CAS  PubMed  PubMed Central  Google Scholar 

  42. Logunov DY, Dolzhikova IV, Zubkova OV, et al. Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia. Lancet, 2020,396(10255):887–897

    CAS  PubMed  PubMed Central  Google Scholar 

  43. Chung YH, Beiss V, Fiering SN, et al. COVID-19 Vaccine Frontrunners and Their Nanotechnology Design. ACS Nano, 2020,14(10):12 522–12 537

    CAS  Google Scholar 

  44. Wadman M. The long shot. Science, 2020,370(6517):649–653

    CAS  PubMed  Google Scholar 

  45. Medhi R, Srinoi P, Ngo N, et al. Nanoparticle-Based Strategies to Combat COVID-19. ACS Appl Nano Mater, 2020,3(9)8557–8580

    CAS  Google Scholar 

  46. Ashraf MU, Kim Y, Kumar S, et al. COVID-19 Vaccines (Revisited) and Oral-Mucosal Vector System as a Potential Vaccine Platform. Vaccines, 2021,9(2):171

    CAS  PubMed  PubMed Central  Google Scholar 

  47. Moore AC, Dora EG, Peinovich N, et al. Preclinical studies of a recombinant adenoviral mucosal vaccine to prevent SARS-CoV-2 infection. bioRxiv, 2020.09.04.283853; doi: https://doi.org/10.1101/2020.09.04.283853

  48. Cubuk J, Alston JJ, Incicco JJ, et al. The SARS-CoV-2 nucleocapsid protein is dynamic, disordered, and phase separates with RNA. Nat Commun, 2021,12(1):1936

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Nooraei S, Bahrulolum H, Hoseini ZS, et al. Viruslike particles: preparation, immunogenicity and their roles as nanovaccines and drug nanocarriers. J Nanobiotechnology, 2021,19(1):59

    CAS  PubMed  PubMed Central  Google Scholar 

  50. Mahmood N, Nasir SB, Hefferon K. Plant-Based Drugs and Vaccines for COVID-19. Vaccines, 2020,9(1):15

    PubMed  PubMed Central  Google Scholar 

  51. Khoury DS, Cromer D, Reynaldi A, et al. Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection. Nat Medicine, 2021. doi: https://doi.org/10.1038/s41591-021-01377-8. Epub ahead of print. PMID: 34002089.

  52. Wu K, Werner AP, Koch M, et al. Serum Neutralizing Activity Elicited by mRNA-1273 Vaccine. N Engl J Med, 2021,384(15):1468–1470

    PubMed  Google Scholar 

  53. van Oosterhout C, Hall N, Ly H, et al. COVID-19 evolution during the pandemic— Implications of new SARS-CoV-2 variants on disease control and public health policies. Virulence, 2021,12(1):507–508

    CAS  PubMed  PubMed Central  Google Scholar 

  54. Abdool Karim SS, de Oliveira T. New SARS-CoV-2 Variants—Clinical, Public Health, and Vaccine Implications. N Engl J Med, 2021,384(19):1866–1868

    PubMed  Google Scholar 

  55. Zou J, Xie X, Fontes-Garfias CR, et al. The effect of SARS-CoV-2 D614G mutation on BNT162b2 vaccrne-elicited neutralization. NPJ Vaccines, 2021,6(1):44

    CAS  PubMed  PubMed Central  Google Scholar 

  56. Korber B, Fischer WM, Gnanakaran S, et al. Tracking Changes in SARS-CoV-2 Spike: Evidence that D614G Increases Infectivity of the COVID-19 Virus. Cell, 2020,182(4):812–827.e19

    CAS  PubMed  PubMed Central  Google Scholar 

  57. Plante JA, Liu Y, Liu J, et al. Spike mutation D614G alters SARS-CoV-2 fitness. Nature, 2021,592(7852):116–121

    CAS  PubMed  Google Scholar 

  58. Planas D, Bruel T, Grzelak L, et al. Sensitivity of infectious SARS-CoV-2 B.1.1.7 and B.1.351 variants to neutralizing antibodies. Nat Med, 2021,27(5):917–924

    CAS  PubMed  Google Scholar 

  59. Shen X, Tang H, McDanal C, et al. SARS-CoV-2 variant B.1.1.7 is susceptible to neutralizing antibodies elicited by ancestral spike vaccines. Cell Host Microbe, 2021,29(4):529–539.e3

    CAS  PubMed  PubMed Central  Google Scholar 

  60. Supasa P, Zhou D, Dejnirattisai W, et al. Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera. Cell, 2021,184(8):2201–2211.e7

    CAS  PubMed  PubMed Central  Google Scholar 

  61. Zhou H, Dcosta BM, Samanovic MI, et al. B.1.526 SARS-CoV-2 variants identified in New York City are neutralized by vaccine-elicited and therapeutic monoclonal antibodies. bioRxiv, 2021.03.24.436620; doi: https://doi.org/10.1101/2021.03.24.436620

  62. Annavajhala MK, Mohri H, Zucker JE, et al. A Novel SARS-CoV-2 Variant of Concern, B.1.526, Identified in New York. medRxiv, 2021.02.23.21252259. doi: https://doi.org/10.1101/2021.02.23.21252259

  63. Greaney AJ, Loes AN, Crawford KHD, et al. Comprehensive mapping of mutations in the SARS-CoV-2 receptor-binding domain that affect recognition by polyclonal human plasma antibodies. Cell Host Microbe, 2021,29(3):463–476.e6

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Kuzmina A, Khalaila Y, Voloshin O, et al. SARS-CoV-2 spike variants exhibit differential infectivity and neutralization resistance to convalescent or postvaccination sera. Cell Host Microbe, 2021,29(4):522–528.e2

    CAS  PubMed  PubMed Central  Google Scholar 

  65. Edara VV, Norwood C, Floyd K, et al. Infection- and vaccine-induced antibody binding and neutralization of the B.1.351 SARS-CoV-2 variant. Cell Host Microbe, 2021,29(4):516–521.e3

    CAS  PubMed  PubMed Central  Google Scholar 

  66. Shinde V, Bhikha S, Hoosain Z, et al. Efficacy of NVX-CoV2373 Covid-19 Vaccine against the B.1.351 Variant. N Engl J Med, 2021,384(20):1899–1909

    CAS  PubMed  PubMed Central  Google Scholar 

  67. Madhi SA, Baillie V, Cutland CL, et al. Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant. N Engl J Med, 2021,384(20):1885–1898

    CAS  PubMed  Google Scholar 

  68. Toovey OTR, Harvey KN, Bird PW, et al. Introduction of Brazilian SARS-CoV-2 484K.V2 related variants into the UK. J Infect, 2021,82(5):e23–e4

    CAS  PubMed  PubMed Central  Google Scholar 

  69. Sapkal G, Yadav PD, Ella R, et al. Neutralization of B.1.1.28 P2 variant with sera of natural SARS-CoV-2 infection and recipients of BBV152 vaccine. bioRxiv, 2021,04.30.441559. doi: https://doi.org/10.1101/2021.04.30.441559

  70. Garcia-Beltran WF, Lam EC, St Denis K, et al. Circulating SARS-CoV-2 variants escape neutralization by vaccine-induced humoral immunity. medRxiv, 2021.02.14.21251704. doi: https://doi.org/10.1101/2021.02.14.21251704

  71. Hirotsu Y, Omata M. Discovery of SARS-CoV-2 strain of P.1 lineage harboring K417T/E484K/N501Y by whole genome sequencing in the city, Japan. medRxiv, 2021.02.24.21251892. doi: https://doi.org/10.1101/2021.02.24.21251892

  72. Dejnirattisai W, Zhou D, Supasa P, et al. Antibody evasion by the P.1 strain of SARS-CoV-2. Cell, 2021, 184(11):2939–2954

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Cherian S, Potdar V, Jadhav S, et al. Convergent evolution of SARS-CoV-2 spike mutations, L452R, E484Q and P681R, in the second wave of COVID-19 in Maharashtra, India. bioRxiv, 2021.04.22.440932. doi: https://doi.org/10.1101/2021.04.22.440932

  74. Motozono C, Toyoda M, Zahradnik J, et al. An emerging SARS-CoV-2 mutant evading cellular immunity and increasing viral infectivity. bioRxiv, 2021.04.02.438288. doi: https://doi.org/10.1101/2021.04.02.438288

  75. Deng X, Garcia-Knight MA, Khalid MM, et al. Transmission, infectivity, and antibody neutralization of an emerging SARS-CoV-2 variant in California carrying a L452R spike protein mutation. medRxiv, 2021.03.07.21252647. doi: https://doi.org/10.1101/2021.03.07.21252647

  76. Nazir SUR, Nazir T, Sultana M, et al. The Potentially Recommended Pharmacotherapy for COVID-19. Altern Ther Health Med, 2021,27(S1):24–28

    PubMed  Google Scholar 

  77. Drożdżal S, Rosik J, Lechowicz K, et al. FDA approved drugs with pharmacotherapeutic potential for SARS-CoV-2 (COVID-19) therapy. Drug Resist Updat, 2020,53:100719

    PubMed  PubMed Central  Google Scholar 

  78. Kokic G, Hillen HS, Tegunov D, et al. Mechanism of SARS-CoV-2 polymerase stalling by remdesivir. Nat Commun, 2021,12(1):279

    CAS  PubMed  PubMed Central  Google Scholar 

  79. Beigel JH, Tomashek KM, Dodd LE, et al. Remdesivir for the Treatment of Covid-19—Final Report. N Engl J Med, 2020,383(19):1813–1826

    CAS  PubMed  PubMed Central  Google Scholar 

  80. White KM, Rosales R, Yildiz S, et al. Plitidepsin has potent preclinical efficacy against SARS-CoV-2 by targeting the host protein eEF1A. Science, 2021, 371(6532):926–931

    CAS  PubMed  PubMed Central  Google Scholar 

  81. Martinez MA. Plitidepsin: a Repurposed Drug for the Treatment of COVID-19. Antimicrob Agents Chemother, 2021,65(4)e00200–21

    CAS  PubMed  PubMed Central  Google Scholar 

  82. Cox RM, Wolf JD, Plemper RK. Therapeutically administered ribonucleoside analogue MK-4482/EIDD-2801 blocks SARS-CoV-2 transmission in ferrets. Nat Microbiol, 2021,6(1):11–18

    CAS  PubMed  Google Scholar 

  83. Gottlieb RL, Nirula A, Chen P, et al. Effect of Bamlanivimab as Monotherapy or in Combination With Etesevimab on Viral Load in Patients With Mild to Moderate COVID-19: A Randomized Clinical Trial. JAMA, 2021,325(7):632–644

    CAS  PubMed  PubMed Central  Google Scholar 

  84. Deb P, Molla MMA, Saif-Ur-Rahman KM. An update to monoclonal antibody as therapeutic option against COVID-19. Biosafety Health, 2021,3(2):87–91

    PubMed  Google Scholar 

  85. Li R, Ma X, Deng J, et al. Differential efficiencies to neutralize the novel mutants B.1.1.7 and 501Y.V2 by collected sera from convalescent COVID-19 patients and RBD nanoparticle-vaccinated rhesus macaques. Cell Mol Immunol, 2021,18(4):1058–1060

    CAS  PubMed  Google Scholar 

  86. Acharya KP, Ghimire TR, Subramanya SH. Access to and equitable distribution of COVID-19 vaccine in low-income countries. NPJ Vaccines, 2021,6(1):54

    CAS  PubMed  PubMed Central  Google Scholar 

  87. Quast I, Tarlinton D. B cell memory: understanding COVID-19. Immunity, 2021,54(2):205–210

    CAS  PubMed  PubMed Central  Google Scholar 

  88. Rahimi H, Salehiabar M, Barsbay M, et al. CRISPR Systems for COVID-19 Diagnosis. ACS Sens, 2021, 6(4):1430–1445

    CAS  PubMed  Google Scholar 

Download references

Author information

Author notes

  1. These authors contribute equally to this work.

Affiliations

  1. Department of Biomedical Sciences, West Virginia School of Osteopathic Medicine, 400 Lee Street North, Lewisburg, West Virginia, 24901, USA

    Lauren Forchette, William Sebastian & Tuoen Liu

Authors
  1. Lauren Forchette
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. William Sebastian
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Tuoen Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Tuoen Liu.

Additional information

Conflict of Interest Statement

The authors whose names are listed in the manuscript certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Forchette, L., Sebastian, W. & Liu, T. A Comprehensive Review of COVID-19 Virology, Vaccines, Variants, and Therapeutics. CURR MED SCI 41, 1037–1051 (2021). https://doi.org/10.1007/s11596-021-2395-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11596-021-2395-1

Key words

  • severe acute respiratory syndrome coronavirus 2
  • coronavirus disease 2019
  • vaccines
  • variant strains
  • antiviral therapy