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SARS-CoV-2 Vaccine

SARS-CoV-2 Vaccine With the SARS-CoV-2 pandemic creating such a wide-reaching health crisis, it is imperative that a safe and effective vaccine be developed promptly for global availability. As such, there are several vaccine development projects currently underway aiming to meet this critical demand. However, COVID vaccine development is not immune to the inherent limitations and challenges that are encountered during vaccine clinical trials. Keywords: SARS-CoV-2 vaccine, COVID vaccine, Coronavirus vaccine Unlike the SARS-CoV-1 epidemic in 2003, which largely remained facing a worldwide COVID pandemic. There is virtually no corner local and quickly vanished from the circulation, SARS-CoV-2 of the world that this highly infectious virus has not touched and [1] succeeded in rapidly spreading globally . As a result, we are there is no certainty regarding when or whether this pandemic will Table 1 [2,3] Different vaccine platforms currently being investigated for SARS-CoV-2 and their benefits/limitations . Teams Currently Working Vaccine Platform Description Benefits Limitations on this Vaccine Platform Virus vaccines Used in measles and polio vaccines Require extensive safety testing 7 teams Weakened Passed through animal or human cells to pick up Codagenix (NY)/Serum Institute mutations that make it less able to cause of India disease Inactivated Chemicals or heat used to make uninfectious Need to start with large quantity of infectious Sinovac Biotech (Beijing) virus Nucleic-acid vaccines Inject genetic instructions coding for mRNA to Safe and easy to develop Unproven, no licensed vaccines use this At least 20 teams (DNA or RNA) make coronavirus proteins to prompt an Generated quickly technology Example: Moderna immune response. (most are spike protein) Make genetic material only (not virus) BioNTech/Pfizer CureVac (mRNA) Inovio (DNA) Viral-vector vaccines Weakened virus (measles, VZV or AV) engineered 25 teams to make coronavirus proteins after injected into the body Replicating Virus that can still replicate within cells Safe Existing immunity to vector virus could blunt Janssen Pharmaceuticals Provoke strong immune response vaccine’s effectiveness Potential for large scale manufacturing Example: Ebola vaccine Nonreplicating Virus that cannot replicate because key genes Long history of use in gene therapy No licensed vaccines Johnson & Johnson have been disabled Booster shots needed for long-immunity Protein-based vaccines Example: hepatitis B, HPV, VZV, and Requires time to establish cell lines for (traditional) influenza manufacturing Protein subunits Fragments of coronavirus proteins injected into Similar SARS vaccines protect monkeys Requires adjuvants to stimulate the immune 28 teams the body (most focusing on spike protein or its against SARS but not tested in people system Example: Sanofi receptor binding domain) May need multiple doses of vaccine Novavax Virus-like particles (VLP) Empty virus shells that mimic coronavirus injected Not infectious because lack genetic material Can be difficult to manufacture 5 teams into the body Can trigger a strong immune response Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. National Institute of Child Health and Human Development, Rockville, MD *Corresponding author. Address: National Institute of Child Health and Human Development, 14314 Chesterfield Road, Rockville, MD 20853. Tel: 309-533-5603; fax: 301- 400-1800. E-mail address: kawalker@atsu.edu (K. Walker). Copyright © 2020 The Authors. Published by Wolters Kluwer on behalf of the International Federation of Fertility Societies. Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government. Global Reproductive Health (2020) 5:e42 Received 23 June 2020; Accepted 7 July 2020 Published online 2 September 2020 http://dx.doi.org/10.1097/GRH.0000000000000042 1 Walker. Global Reproductive Health (2020) 5:e42 Global Reproductive Health Normally, 12–18 months is required to develop a new vaccine Table 2 [1] (development, clinical trials, and regulatory approval) . To date, [2] Possible hurtles/limitations to clinical trials creating a vaccine . upwards of ninety different vaccines are undergoing development Theoretical risk of vaccination causing subsequent increased infection severity from groups around the world to fight SARS-CoV-2. At least 6 of Example: Vaccine-associated enhanced respiratory disease these groups have started to test the safety and efficacy in human [3] No in vivo data on type or level of immunity required to protect from subsequent volunteers . Many vaccine platforms are being utilized in this reinfection and duration of that protection global effort, which all have unique advantages and limitations Trial needs prolonged follow-up of initial vaccine cohort to determine durability of (Table 1). Overall, vaccine characteristics that are needed immunity include: speed and flexibility of manufacturing, safety and reac- Need for testing parameters to distinguish immune response from prior vaccine togenicity, production of humoral and cellular immunogenicity, versus infection durability of immunity, appropriate scale and cost of manu- [2] High mutation rate of single-stranded RNA virus such as SARS-CoV-2 (Genetic drift) facturing, vaccine stability and cold chain requirements . While Though to date, only limited alterations seen in the spike protein this swift movement with maximal globally-involved efforts toward vaccine development is encouraging, there are still many 20%–40% of total COVID-19 cases are asymptomatic Would need a greater number of trial enrollees as exact incidence rates are unknown challenges to face before a vaccine can be made widely available (Table 2). Partial efficacy in a young healthy adult does not predict similar effectiveness amount older adults with comorbidities Trial inclusion population requires both younger and older populations Conflict of interest disclosures The author declares that there is no financial conflict of interest end. With this wide-reaching health crisis, there is an unprece- with regard to the content of this report. dented need for development of a safe and effective vaccine that [2] can be made globally available . There are 2 primary goals in a References development of a vaccine: (1) protection from infection due to seroconversion and (2) prevention of clinically symptomatic dis- [1] Wang F, Kream RM, Stefano GB. An evidence based perspective on mRNA-SARS-CoV-2 vaccine development. Med Sci Monit 2020;26: ease (especially amelioration of severe disease that requires high [2] e924700. intensity medical care and taxes the medical system) . If a vaccine [2] Corey BL, Mascola JR, Fauci AS, et al. A strategic approach to COVID-19 succeeds in hitting these 2 aims, then we will see a reduced popu- vaccine R&D. Science 2020;368:948. lation transmissibility and prevention of secondary epidemics or [3] Callaway E. The race for coronavirus vaccines: a graphical guide. Nature pandemics. 2020;580:576–7. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Global Reproductive Health Pubmed Central

SARS-CoV-2 Vaccine

Global Reproductive Health , Volume 5 – Sep 2, 2020

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References (7)

Publisher
Pubmed Central
Copyright
Copyright © 2020 The Authors. Published by Wolters Kluwer on behalf of the International Federation of Fertility Societies.
ISSN
2473-3709
eISSN
2473-3709
DOI
10.1097/GRH.0000000000000042
Publisher site
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Abstract

With the SARS-CoV-2 pandemic creating such a wide-reaching health crisis, it is imperative that a safe and effective vaccine be developed promptly for global availability. As such, there are several vaccine development projects currently underway aiming to meet this critical demand. However, COVID vaccine development is not immune to the inherent limitations and challenges that are encountered during vaccine clinical trials. Keywords: SARS-CoV-2 vaccine, COVID vaccine, Coronavirus vaccine Unlike the SARS-CoV-1 epidemic in 2003, which largely remained facing a worldwide COVID pandemic. There is virtually no corner local and quickly vanished from the circulation, SARS-CoV-2 of the world that this highly infectious virus has not touched and [1] succeeded in rapidly spreading globally . As a result, we are there is no certainty regarding when or whether this pandemic will Table 1 [2,3] Different vaccine platforms currently being investigated for SARS-CoV-2 and their benefits/limitations . Teams Currently Working Vaccine Platform Description Benefits Limitations on this Vaccine Platform Virus vaccines Used in measles and polio vaccines Require extensive safety testing 7 teams Weakened Passed through animal or human cells to pick up Codagenix (NY)/Serum Institute mutations that make it less able to cause of India disease Inactivated Chemicals or heat used to make uninfectious Need to start with large quantity of infectious Sinovac Biotech (Beijing) virus Nucleic-acid vaccines Inject genetic instructions coding for mRNA to Safe and easy to develop Unproven, no licensed vaccines use this At least 20 teams (DNA or RNA) make coronavirus proteins to prompt an Generated quickly technology Example: Moderna immune response. (most are spike protein) Make genetic material only (not virus) BioNTech/Pfizer CureVac (mRNA) Inovio (DNA) Viral-vector vaccines Weakened virus (measles, VZV or AV) engineered 25 teams to make coronavirus proteins after injected into the body Replicating Virus that can still replicate within cells Safe Existing immunity to vector virus could blunt Janssen Pharmaceuticals Provoke strong immune response vaccine’s effectiveness Potential for large scale manufacturing Example: Ebola vaccine Nonreplicating Virus that cannot replicate because key genes Long history of use in gene therapy No licensed vaccines Johnson & Johnson have been disabled Booster shots needed for long-immunity Protein-based vaccines Example: hepatitis B, HPV, VZV, and Requires time to establish cell lines for (traditional) influenza manufacturing Protein subunits Fragments of coronavirus proteins injected into Similar SARS vaccines protect monkeys Requires adjuvants to stimulate the immune 28 teams the body (most focusing on spike protein or its against SARS but not tested in people system Example: Sanofi receptor binding domain) May need multiple doses of vaccine Novavax Virus-like particles (VLP) Empty virus shells that mimic coronavirus injected Not infectious because lack genetic material Can be difficult to manufacture 5 teams into the body Can trigger a strong immune response Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. National Institute of Child Health and Human Development, Rockville, MD *Corresponding author. Address: National Institute of Child Health and Human Development, 14314 Chesterfield Road, Rockville, MD 20853. Tel: 309-533-5603; fax: 301- 400-1800. E-mail address: kawalker@atsu.edu (K. Walker). Copyright © 2020 The Authors. Published by Wolters Kluwer on behalf of the International Federation of Fertility Societies. Written work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a “work of the United States Government” for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government. Global Reproductive Health (2020) 5:e42 Received 23 June 2020; Accepted 7 July 2020 Published online 2 September 2020 http://dx.doi.org/10.1097/GRH.0000000000000042 1 Walker. Global Reproductive Health (2020) 5:e42 Global Reproductive Health Normally, 12–18 months is required to develop a new vaccine Table 2 [1] (development, clinical trials, and regulatory approval) . To date, [2] Possible hurtles/limitations to clinical trials creating a vaccine . upwards of ninety different vaccines are undergoing development Theoretical risk of vaccination causing subsequent increased infection severity from groups around the world to fight SARS-CoV-2. At least 6 of Example: Vaccine-associated enhanced respiratory disease these groups have started to test the safety and efficacy in human [3] No in vivo data on type or level of immunity required to protect from subsequent volunteers . Many vaccine platforms are being utilized in this reinfection and duration of that protection global effort, which all have unique advantages and limitations Trial needs prolonged follow-up of initial vaccine cohort to determine durability of (Table 1). Overall, vaccine characteristics that are needed immunity include: speed and flexibility of manufacturing, safety and reac- Need for testing parameters to distinguish immune response from prior vaccine togenicity, production of humoral and cellular immunogenicity, versus infection durability of immunity, appropriate scale and cost of manu- [2] High mutation rate of single-stranded RNA virus such as SARS-CoV-2 (Genetic drift) facturing, vaccine stability and cold chain requirements . While Though to date, only limited alterations seen in the spike protein this swift movement with maximal globally-involved efforts toward vaccine development is encouraging, there are still many 20%–40% of total COVID-19 cases are asymptomatic Would need a greater number of trial enrollees as exact incidence rates are unknown challenges to face before a vaccine can be made widely available (Table 2). Partial efficacy in a young healthy adult does not predict similar effectiveness amount older adults with comorbidities Trial inclusion population requires both younger and older populations Conflict of interest disclosures The author declares that there is no financial conflict of interest end. With this wide-reaching health crisis, there is an unprece- with regard to the content of this report. dented need for development of a safe and effective vaccine that [2] can be made globally available . There are 2 primary goals in a References development of a vaccine: (1) protection from infection due to seroconversion and (2) prevention of clinically symptomatic dis- [1] Wang F, Kream RM, Stefano GB. An evidence based perspective on mRNA-SARS-CoV-2 vaccine development. Med Sci Monit 2020;26: ease (especially amelioration of severe disease that requires high [2] e924700. intensity medical care and taxes the medical system) . If a vaccine [2] Corey BL, Mascola JR, Fauci AS, et al. A strategic approach to COVID-19 succeeds in hitting these 2 aims, then we will see a reduced popu- vaccine R&D. Science 2020;368:948. lation transmissibility and prevention of secondary epidemics or [3] Callaway E. The race for coronavirus vaccines: a graphical guide. Nature pandemics. 2020;580:576–7.

Journal

Global Reproductive HealthPubmed Central

Published: Sep 2, 2020

There are no references for this article.