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.