Particularly earlier on in the pandemic, there was a lot of media attention relating

to various experimental therapies for COVID-19 including antiviral agents,

immunomodulators, anticoagulants, anti-inflammatories, etc. [2]. None of these

pharmacotherapeutic modalities, as of the writing of this chapter, have proven to be

effective, and besides systemic steroids in the case of SIRS and cytokine storm,

COVID-19 continues to be treated symptomatically. Therefore, the current best

strategy to ending this pandemic continues to be mass vaccination.

12.4

VACCINE DEVELOPMENT FOR SARS-COV-2

As previously detailed in Chapter 3, vaccines contain antigens in some form, either

genetic or proteinaceous; and by exposing an individual to an inert antigen of in-

terest, the immune system can be primed to recognize the pathogen in the event of a

future infection. A good vaccine will create long-lasting immunity through both

cellular and humoral memory in the form of T-cells and antibodies, respectively.

As previously discussed in Chapter 2, each virus is unique in terms of its route of

infection, the types of cells it infects, and subsequently its clinical pathology. As

such, the immune response required to fight off a virus will be unique to each

type [18]. This understanding of the way the immune system controls a natural

infection is crucial when designing a vaccine against a particular virus. Simply put,

if the immune response elicited by a vaccine is not optimal for a given virus, it will

not offer much protection against a natural infection.

Since the discovery of the first vaccine in the 18th century, the conventional

platform for most vaccines have been either inactivated viruses (IVs) or live atte-

nuated viruses (LAVs). These have generally been very successful techniques, as

detailed in Chapter 9 and will be expanded upon below [19]. Despite their great

success in controlling and even eradicating certain diseases, their use has always

been limited in the control of pandemics and epidemics [2]. This is largely due to

the labor-intensive production process, which imposes constraints on the amount of

vaccine that could be produced, and the time required to produce it. Therefore, it is

perhaps unsurprising that it was the new vaccine technologies that were the first

available in the COVID-19 pandemic.

Unlike other therapeutics, vaccines are administered into healthy individuals.

Therefore, the margins of safety must be extremely high for the public to willingly

accept being injected with a foreign substance to gain protection against a pathogen

that they may one day encounter [18]. The process of thorough examination that

vaccines undergo for their development and approval normally takes 10–15 years.

The process is as follows: [4,20,21]:

• Exploratory and pre-clinical phase (2–3 years): This stage begins with

basic labwork and computational modeling to identify a vaccine candidate.

Experiments are then performed on in vitro cell/tissue models to establish

proof of concept and safety. If this is successful, the next step is experi-

ments on animal models.

•

Phase I clinical trials (2–3 years): The focus of this phase is safety, do-

sage, and immunogenicity. These are the first experiments performed in

COVID-19 vaccines

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