8. Vaccine production process and COVID-19
Vaccines are the most effective means to prevent and control infectious diseases economically (Remy et al., 2014). In this pandemic all eyes are on the research institutions and the pharmaceutical companies involved in COVID-19 vaccine development. However, the vaccine production process has to follow the set stringent principles laid by various regulating agencies and a successful SARS-CoV-2 vaccine could not be achieved overnight. The biological characteristics of SARS-CoV-2 such as epidemiology, structural basis, pathogenesis, correlates of immunity, immune-pathologies, etc are still unclear (Zhang et al., 2020). Generally, normal vaccine development takes a decade or two with very less success rate but there is a broad consensus between the scientists worldwide regarding the availability of vaccine against SARS-CoV-2 which is expected to be 12-18 moths away (Dresden, 2020). It is because the identification of SARS-CoV-2 was done within 3 months of its spread and the study of its other biological characteristics is undergoing very vigorously to develop the whole information which will potentially facilitate the rapid development of its vaccine. Globally, confirmed COVID-19 cases are still increasing at an alarming rate and it may potentially become a flu-like seasonal disease and remain in coexistence with human beings for a long time (Neher et al., 2020). Thus, vaccine development is necessary even if it is occurring at a slower pace than the spreading of COVID-19 pandemic. Once a potential vaccine is announced by a researcher, a prospective producer pharmaceutical company has to submit an application to a regulatory authority such as Food and Drug Administration (FDA) for investigation of the new vaccine. The application must describe the vaccine, its manufacturing process, its safety, and efficacy in animal testing (Dresden, 2020). Broadly the vaccine production process can be classified into following stages (Ryan, 2020):
a) Vaccine design: A researcher studies the relevant pathogen characteristics, selects most suitable antigenic fragment, and makes that antigen get expressed preferably to get recognized by host immune system.
b) Animal studies: The new proposed vaccine is tested in animal models to study immune responses, efficacy, and safety upon immunization. The correlates of immunity, immuno-pathologies, and level of protection conferred on challenge are also studied.
c) Clinical trials (phase I): After successfully passing the animal studies similar investigations are carried out in a small cohort of patients or volunteers. The dose and side effects of the vaccine are also studied.
d) Clinical trials (phase II): This stage involves a deeper analysis of vaccine biology and mechanism of action over a larger cohort of patients.
e) Clinical trials (phase III): This phase is similar to phase II but has a greater coverage of people under testing over a longer period of time to generate large amount of data to draw valid statistical conclusions. This phase also explores any possible late adverse effects of immunization.
f) Regulatory approval: The regulatory agency takes a final call regarding approval of the studied vaccine as a treatment option for the disease. Regulatory agency strictly carries out scrutiny of the evidences and the data on animal and human trials with the proposed vaccine to make a final decision on its suitability as a treatment option. Traditionally, it takes a decade or two for a new vaccine to go from a design to approval stage (Ryan, 2020) but the process of vaccine development against COVID-19 has briskly reached the phase II clinical trial at various places worldwide and it is expected to be the fastest vaccine ever produced in human history.