A Review of COVID-19 Vaccines in Development: 6 Months Into the Pandemic
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Article Review A review of COVID-19 vaccines in development: 6 months into the pandemic Merlin Sanicas, Melvin Sanicas, Doudou Diop, Emanuele Montomoli Corresponding author: Doudou Diop, PATH, Dakar, Sénégal. [email protected] Received: 13 Jul 2020 - Accepted: 29 Jul 2020 - Published: 05 Oct 2020 Keywords: Coronavirus, COVID-19, pandemic, vaccine development Copyright: Merlin Sanicas et al. Pan African Medical Journal (ISSN: 1937-8688). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Cite this article: Merlin Sanicas et al. A review of COVID-19 vaccines in development: 6 months into the pandemic. Pan African Medical Journal. 2020;37(124). 10.11604/pamj.2020.37.124.24973 Available online at: https://www.panafrican-med-journal.com/content/article/37/124/full A review of COVID-19 vaccines in development: 6 Abstract months into the pandemic 1 2 3,& The advent of the COVID-19 pandemic and the Merlin Sanicas , Melvin Sanicas , Doudou Diop , dynamics of its spread is unprecedented. 4,5 Emanuele Montomoli Therefore, the need for a vaccine against the virus is huge. Researchers worldwide are working 1Centre de Recherche en Cancérologie de around the clock to find a vaccine. Experts Marseille, Université Aix-Marseille, Marseille, 2 estimate that a fast-tracked vaccine development France, Clinical Development, Takeda process could speed a successful candidate to Pharmaceuticals International AG, Zurich, 3 4 market in approximately 12-18 months. The Switzerland, PATH, Dakar, Sénégal, Department objective of this review was to describe the of Molecular and Developmental Medicine, 5 coronavirus vaccines candidates in development University of Siena, Siena, Italy, VisMederi Life and the important considerations. The review was Science Research, Siena, Italy conducted through a thematic analysis of the literature on COVID-19 vaccines in development. It &Corresponding author only included data until the end of June 2020, 6 Doudou Diop, PATH, Dakar, Sénégal Merlin Sanicas et al. PAMJ - 37(124). 05 Oct 2020. - Page numbers not for citation purposes. 1 Article months after the emergence of the COVID-19. Methods Different approaches are currently used to develop COVID-19 vaccines from traditional live- This review was conducted through a thematic attenuated, inactivated, subunit vaccines, to more analysis of the literature on COVID-19 vaccines in novel technologies such as DNA or mRNA vaccines. development. The review is conceptual and The race is on to find both medicines and vaccines focuses on the WHO COVID-19 vaccines landscape, for the COVID-19 pandemic. As with drugs, vaccine clinicaltrials.gov, media reports, and the respective candidates go through pre-clinical testing first websites of companies reported to be working on before they go through the three phases of clinical a COVID-19 vaccine. The review only included data trials in humans. Of the over 130 vaccine until the end of June 2020, 6 months after the candidates, 17 are in clinical trials while others are emergence of the novel coronavirus, SARS-CoV-2. expected to move to clinical testing after the animal studies. Current status of knowledge Introduction There are different types of vaccines in development for COVID-19. The pipeline includes Coronavirus is spreading around the world. As of over 130 candidates in development and as of end th July 12 , 2020, more than 12,552,736 cases of June 2020, 17 are already in various phases of COVID-19 have been reported in over 216 clinical development, while the others are in countries and territories, resulting in 561,617 preclinical development. Each of the different deaths [1, 2]. The virus spreads easily and most of vaccine platforms available, traditional, or novel, is the world's population is still vulnerable to it. It is currently being explored. The World Health therefore, of paramount importance to get a Organization (WHO) landscape of COVID-19 vaccine that can stop the spread of the virus. vaccine candidates (19 June 2020) lists 136 vaccine Researchers are working hard to control the candidates [3]. Researchers striving to develop a pandemic. We are only over 6 months after the coronavirus vaccine are working with different current outbreak was first reported from Wuhan, approaches, all with their respective advantages China yet the virus SARS-CoV-2 has been and disadvantages (Figure 1). Live attenuated identified, sequenced, and shared to the whole vaccine [4, 5]; inactivated vaccine [5]; vector- world. This is unprecedented for a new disease. based vaccine [6]; protein subunit vaccine [7]; DNA Rapidly advancing potential vaccines is critical to vaccine [6-11] and mRNA vaccines [6]. The stemming the virus´s devastating impact on sections below will discuss these different vaccine human health and the global economy. A vaccine approaches. A summary of all the vaccine would provide some protection by training candidates currently in clinical trials is provided in people's immune systems to fight the virus so they Table 1. should not become sick. Besides the anticipated health benefits from a coronavirus vaccine, there Live-attenuated vaccine: live-attenuated vaccines are several impacts on economic and social use an altered version of SARS-CoV-2 so that it is aspects. This would allow lockdowns to be lifted less virulent (Table 2). These vaccines are very more safely, and social distancing to be relaxed. effective, and a single dose is often enough to The objective of this review was to describe the induce long-lasting immunity. Serum Institute of coronavirus vaccines candidates in development India has partnered with US-based clinical-stage and the important considerations. biotechnology company Codagenix to co-develop a live-attenuated vaccine against the coronavirus. Viruses will then be grown and tested in vivo by contracted laboratories suitable for containment, Merlin Sanicas et al. PAMJ - 37(124). 05 Oct 2020. - Page numbers not for citation purposes. 2 Article prior to testing in clinical trials [12]. Griffith Newcastle Disease Virus. Non-replicating viral University is working with Indian Immunologicals vectors include: adenovirus, Modified Vaccinia Limited to develop a live attenuated vaccine using Ankara (MVA), influenza, parainfluenza, and a codon de-optimization technology to change the rabies [3]. virus´s genome and decrease the replication efficiency in human cells [13]. The German Center China´s CanSino Biologics was the first company in for Infection Research is working on an attenuated the world to begin a clinical study of a SARS-CoV-2 virus (MVA: modified vaccinia virus Ankara), which vaccine. Less than 10 weeks later, the company had previously been used in a smallpox eradication published the Phase 1 trial data. The vaccine vaccination campaign [14]. candidate, using a genetically engineered adenovirus vector to deliver the gene that encodes Inactivated vaccine: inactivated (or killed) the SARS-CoV-2 spike protein into human cells. vaccines consist of pathogens inactivated through CanSino measured neutralizing antibodies physical, chemical, or biological means (Table 2). concentrations in subjects and found that 75% of Beijing-based vaccine manufacturer, Sinovac´s people who received the high dose and 50% of candidate vaccine-called CoronaVac-was tested in those who received a medium or low dose 743 healthy volunteers between 18 and 59 years developed levels of neutralizing antibodies old, including 143 participants in Phase 1 and 600 considered high by the researchers [18]. AZD1222, in Phase 2. The vaccine induced neutralizing developed by Oxford University´s Jenner Institute antibodies in over 90% of volunteers after and the Oxford Vaccine Group, uses a replication- receiving two doses, two weeks apart. Phase 3 deficient chimpanzee viral vector based on an clinical trials are expected to be conducted both attenuated version of a common cold (adenovirus) within China and in countries outside China [15]. virus that causes infections in chimpanzees and Sinopharm´s vaccine candidate, called BBIBP-CorV, contains the genetic material of SARS-CoV-2 spike induced neutralizing antibodies against protein. The vaccine has gone through Phase 1 and SARS-CoV-2 in rodents, rabbits, and monkeys [16]. is starting Phase 2/3 in England and Brazil [19]. China´s Institute of Medical Biology candidate is in Phase 1 while the rest are in pre-clinical [3]. Protein subunit vaccine: instead of the whole pathogen, subunit vaccines include only specific Viral vector vaccine: a vector is another virus that components or antigens that have been proven is not harmful and acts as the delivery system to through pre-clinical studies to stimulate the carry antigens to the immune system. Scientists immune system (Table 4) [20]. Including only design a vector to carry only a small part of the certain antigens in the vaccine can minimize side SARS-CoV-2 genetic material so that it cannot effects but it usually requires the addition of cause infection. Once inside the body, the genetic adjuvants to elicit a stronger immune response material is converted to protein (Table 3). The because antigens alone are not sufficient to elicit advantages of viral vectors are: 1) high efficiency adequate long-term immunity [21]. There are gene transduction; 2) highly specific delivery of several protein-based vaccine