COVID-19 CHALLENGES IN VACCINE DEVELOPMENT-I
Conducting High-Quality COVID -19 Vaccines
Healthcare workers and regulatory authorities have put into severe pressure by the COVID -19
pandemic to swiftly make the vaccine more rapidly. During this crisis it is a heroic but difficult
task for conducting clinical trials, as clinicians have to provide patient care while they are at risk
of encountering infection. As the name suggests, the virus is novel, therefore humans have no
natural immunity to it, and researchers must start to develop a vaccine to educate the immune
system to defend itself from the virus. Numerous pharma and academic institutes are racing to
develop a vaccine against SARS-CoV-2 across the world, including India. There are a few major
hurdles to overcome to create a vaccine against COVID-19.
Vaccine development has played a hugely important role in combating infectious diseases. The
successful eradication of smallpox globally became a new era for the vaccine world. Today, the
term “vaccine” applies to all biological compositions, processed from living organisms that
amplify immunity against disease and either prevent or in some cases, medicate disease. Vaccines
are administered in the liquid form either by injection, by oral, or by intranasal routes. There are
many types of vaccines developed for a variety of diseases around the world at certain times when
it is needed. Some of them are mentioned below:
Types of Vaccines and Examples
Live attenuated: Measles, Mumps, Rubella
Inactivated: Hepatitis-A, Influenza
Recombinant: subunit Hepatitis-B
Toxoid: Tetanus, Diphtheria
Conjugate-polysaccharide-protein: Pneumococcal, Meningococcal
Vaccines help to develop immunity by initiating an infection. This type of infection never causes
illness, but it does cause the immune system to produce T-lymphocytes and antibodies. However,
it typically takes a couple of weeks for the body to supply T- lymphocytes and B- lymphocytes
after vaccination. Therefore, the possibility that a person infected with a disease just before or just
after vaccination could develop symptoms and gets a disease, because the vaccine doesn’t have
enough time to provide protection. Vaccine development efforts make us enlightened for operating
swiftly, and several major vaccine platforms are moving toward clinical evaluation. These include
traditional recombinant protein, replicating and non-replicating viral vectors, and macromolecule
DNA and mRNA approaches. Each of these vaccine platforms has advantages and drawbacks.
The principal attributes include speed and versatility of manufacture, safety and reactogenicity,
the longevity of immunity, scale and price of producing, vaccine stability, and cold chain
requirements. No single vaccine or vaccine platform alone is likely to meet the global need, and so a strategic approach to the multi-pronged endeavor is critical. Traditional recombinant protein
technology is often wont to express the spike protein (e.g., Sanofi, Novavax). Moreover, it takes
much time to determine cell lines needed for manufacturing than for macromolecule vaccinesthere’s a strong commercial experience with protein and protein particle vaccines.
Janssen Pharmaceuticals for COVID-19 developed the replication-defective adenovirus 26
(rAd26), which was recently shown to be safe and immunogenic in preventing Ebola virus
infection. A recombinant chimpanzee Ad vector (ChAdOx1), developed by the University of
Oxford and AstraZeneca, and had also entered clinical trials. Similar versions of ChAd vaccine
products are tested in prior clinical trials and shown to be safe and immunogenic. These manifold
perspectives provide the potential for modular production required for widespread population use.
Corona Virus Vaccine Challenges
There are certain ultimatums for COVID-19 pandemic:
• Ensuring vaccine safety: – Several vaccines for SARS have been tested in animals. Most
of the vaccines improved the animal’s survival but didn’t prevent infection. Some vaccines
also caused complications, such as lung damage. A COVID-19 vaccine will need to be
thoroughly tested to make sure it’s safe for humans.
• Providing long term protection: – After infection with coronavirus, re-infection with the
same virus- though usually mild and only happening in a fraction of people- is possible
after months or years. An effective COVID-19 will need to provide people with long-term
• Protecting old people: – People older than age 60 are at higher risk of severe COVID-19.
But older people usually don’t respond to vaccines as well as younger people. An ideal
COVID-19 vaccine would work well for this age group.
• Highly Mutagenic: – The COVID-19 is highly mutagenic as it frequently changes strain.
Many reports suggest it might change its strain from person to person.