Abstract
The COVID-19 pandemic has infected millions of people with no clear signs of abatement owing to the high prevalence, long incubation period and lack of established treatments or vaccines. Vaccines are the most promising solution to mitigate new viral strains. The genome sequence and protein structure of the 2019-novel coronavirus (nCoV or SARS-CoV-2) were made available in record time, allowing the development of inactivated or attenuated viral vaccines along with subunit vaccines for prophylaxis and treatment. Nanotechnology benefits modern vaccine design since nanomaterials are ideal for antigen delivery, as adjuvants, and as mimics of viral structures. In fact, the first vaccine candidate launched into clinical trials is an mRNA vaccine delivered via lipid nanoparticles. To eradicate pandemics, present and future, a successful vaccine platform must enable rapid discovery, scalable manufacturing and global distribution. Here, we review current approaches to COVID-19 vaccine development and highlight the role of nanotechnology and advanced manufacturing.
Main
In December 2019, a novel coronavirus (nCoV or SARS-CoV-2) belonging to the betacoronavirus family emerged1,2. All human betacoronaviruses are unique from one another, however, they do share a certain degree of genetic and structural homology. SARS-CoV-2 genome sequence homology with SARS-CoV and MERS-CoV is 77% and 50%, respectively3. In contrast to the relatively smaller outbreaks of SARS-CoV in 2002 and MERS-CoV in 2012, SARS-CoV-2 is exhibiting an unprecedented scale of infection, resulting in a global pandemic declaration of Coronavirus Infectious Disease (COVID-19) on 11 March 2020 by the World Health Organization (WHO). On 1 June 2020, the World Health Organization reported >6 million confirmed cases and 371 thousand deaths globally. Of note, during the 1918 influenza pandemic, more death was observed in the second phase of outbreak4. Similar to influenza, COVID-19 harbours the potential to become a seasonal disease5. The high infection rate, long incubation period, along with mild-to-moderate symptoms experienced by many, make COVID-19 a troubling disease. A vaccine is crucial, in particular because data indicate asymptomatic transmission of COVID-196,7,8. More than 10 years ago, scientists predicted the pandemic potential of the coronaviruses9. And for the past 30 years, a once-per-decade novel coronavirus has pushed our public health system to the limit, with SARS-CoV-2 being the most severe. Despite the repeated warnings and discussion, the world was not prepared for this pandemic. The rapid development, distribution and administration of a vaccine to the global population is the most effective approach to quell this pandemic and the only one that will lead to a complete lifting of restrictions. Challenges include the vaccine design itself, but also its manufacture and global distribution; cold chain requirements present logistical and fiscal barriers to the availability of important, life-saving vaccines in resource-poor areas of the world. Innovating vaccine delivery platforms and devices to break cold chain limitations are therefore an efficient solution to safeguard potent vaccination for both wealthy and lower-income countries.
The vaccine strategies
When designing a vaccine, principally, one needs to define the antigen, the adjuvant, the manufacturing system and the delivery strategy (Box 1). The rapid development of vaccines is possible because the genome and structural information of SARS-CoV-2 was made available in record time10,11,12,13,14. These data, along with expedited communication of bioinformatic predictions and epitope mapping15,16,17,18, has provided crucial knowledge enabling vaccine design beyond development of live-attenuated and inactivated vaccines19,20,21,22,23. Also, information available from prior development of SARS/MERS vaccine candidates aids in the development of SARS-CoV-2 vaccine candidates24,25. Nanotechnology platforms offer great utility in modern vaccine design and have helped catalyse novel candidate vaccines toward clinical testing at unprecedented speed. Along with inactivated vaccines, emerging nanotechnologies such as mRNA vaccines delivered by lipid nanoparticles and viral vector vaccines have already reached Phase II and III clinical trials (Fig. 1 and Table 1).
https://pubs.acs.org/doi/10.1021/acsnano.0c07197
Abstract
Humanity is experiencing a catastrophic pandemic. SARS-CoV-2 has spread globally to cause significant morbidity and mortality, and there still remain unknowns about the biology and pathology of the virus. Even with testing, tracing, and social distancing, many countries are struggling to contain SARS-CoV-2. COVID-19 will only be suppressible when herd immunity develops, either because of an effective vaccine or if the population has been infected and is resistant to reinfection. There is virtually no chance of a return to pre-COVID-19 societal behavior until there is an effective vaccine. Concerted efforts by physicians, academic laboratories, and companies around the world have improved detection and treatment and made promising early steps, developing many vaccine candidates at a pace that has been unmatched for prior diseases. As of August 11, 2020, 28 of these companies have advanced into clinical trials with Moderna, CanSino, the University of Oxford, BioNTech, Sinovac, Sinopharm, Anhui Zhifei Longcom, Inovio, Novavax, Vaxine, Zydus Cadila, Institute of Medical Biology, and the Gamaleya Research Institute having moved beyond their initial safety and immunogenicity studies. This review analyzes these frontrunners in the vaccine development space and delves into their posted results while highlighting the role of the nanotechnologies applied by all the vaccine developers.
