Nonhuman primate models for evaluation of SARS-CoV-2 vaccines.

INTRODUCTION: Evaluation of immunogenicity and efficacy in animal models provide critical data in vaccine development. Nonhuman primates (NHPs) have been used extensively in the evaluation of SARS-CoV-2 vaccines. AREAS COVERED: A critical synthesis of SARS-CoV-2 vaccine development with a focus on challenge studies in NHPs is provided. The benefits and drawbacks of the NHP models are discussed. The citations were selected by the authors based on PubMed searches of the literature, summaries from national public health bodies, and press-release information provided by vaccine developers. EXPERT OPINION: We identify several aspects of NHP models that limit their usefulness for vaccine-challenge studies and numerous variables that constrain comparisons across vaccine platforms. We propose that studies conducted in NHPs for vaccine development should use a standardized protocol and, where possible, be substituted with smaller animal models. This will ensure continued rapid progression of vaccines to clinical trials without compromising assessments of safety or efficacy.

Challenges for Vaccinologists in the First Half of the Twenty-First Century.

The COVID-19 pandemic of 2020-2021 has highlighted the importance of vaccines and vaccination in human health. The pandemic has resulted in social distancing, travel restrictions, decreased trade, high unemployment, commodity price decline, and financial stress that has impacted the global economy. Since December 2020, a massive vaccination campaign is undergoing in every country on the planet to protect against SARS-CoV-2. Vaccination is the cheapest health-care interventions that can save more lives than any other drugs or therapies. Some of the common diseases of the twentieth century including smallpox and polio are seldom reported due to intense vaccination programs that eradicated it. Smallpox is completely eradicated globally; whereas, polio is confined to only a couple of countries. Vaccination has not only improved the health of man but also improved food security by preventing diseases in farm animals and aquacultured fish. Awareness of the principles of immunology and novel vaccines has led to effective vaccination strategies. Climate change could lead to generation of new strains of infectious microorganisms that would require development of novel vaccines. Recent years have seen the increase in incidence of brain-eating amoeba and flesh-eating bacteria (necrotizing fasciitis). There are no vaccines for these diseases. Though vaccination programs have eradicated several diseases and increased the quality of life, there are several diseases that have no effective vaccines. Currently there are no vaccines for cancer, neurodegenerative diseases, autoimmune diseases, as well as infectious diseases like tuberculosis, AIDS, and parasitic diseases including malaria. Spontaneous evolution of pathogenic microorganisms may lead to pandemics that impact the health of not only humanity but also other animals. Hence, the challenge to vaccinologists is the development of novel vaccines and vaccination strategies within limited time period and using minimum resources. In addition, the vaccine developed should be administered globally within a short duration so as to prevent generation of pathogenic variants more lethal than the parent strain.