One of the biggest leaps in present times and a significant development of this decade will be the fast track development of a vaccine for a virus that has put the whole world on a halt. Indeed, the arrival of SARS-CoV-2 vaccine will be a monumental breakthrough.
Encouraging results of many frontrunner vaccine manufacturers have made it to the headlines in November. Everyone is awaiting the potential COVID-19 antidote, but what we need to understand, is that even if a vaccine does come out, it will be a long drawn and arduous process to vaccinate 8 billion people across the world.
Currently, there are three families( types) of Coronavirus vaccines that are being developed and to understand the manufacturing and efficacy, we need to understand how vaccines work and how they produce an appropriate immune response in the human body.
What is a vaccine and how does it work?
A vaccine does not provide antibodies but contains weakened or dead microbes which helps the body to initiate an immune response and produce antibodies, without causing any major illness.
In the medical terminology, vaccines deliberately introduce a foreign substance, called an antigen, into the body to induce the body to elicit an immune response. Vaccines don’t confer the protection immediately, but the immunity lasts for a considerably longer period once established.
Hence, repeated doses of the same antigen could boost immunity further. The immune response the second time is even more effective. This memory is known as immunological memory, and it forms the basis of vaccination. That is why the polio vaccine is given to a child multiple times.
Why Vaccine for COVID-19?
As we know that, no virus can ever be killed and coronavirus disease is caused by a virus called SARS-Cov-2, thereby scientists across the world are working day and night to develop a vaccine against SARS-Cov-2, which belongs to the family of viruses called Coronaviridae.
Multiple coronavirus vaccines are being developed as each type of vaccine requires its special process, equipment to make, store and deliver it, thereby it’s important to have multiple kinds of working COVID-19 vaccines so that we can make use of all the resources at the same time.
There are many ways to develop a vaccine. The major ones can be classified into two broad categories –
- Conventional Method ( Live attenuated and inactivated virus vaccines)
Conventional vaccines fall into two broad categories: live attenuated vaccines and inactivated killed vaccines.
- Live attenuated vaccines contain whole virus particles. To develop this vaccine, the virus is injected into an ‘unnatural’ host, causing the virus to eventually lose its adaptation towards the actual host, and transform to a less virulent form. So that it can no longer cause disease as well as it could before. The chickenpox, measles, mumps and rubella vaccines are all live vaccines.
- Inactivated vaccines contain a part of the virus instead of the whole. During preparation, researchers remove those parts of the virus which are required for viral replication. Sometimes, a substance called an adjuvant (to help or aid) is added to inactivated vaccines to boost the immune response.
Coronavirus Vaccines Being Developed by Conventional Method
Some of the major vaccine candidates from this family are US-based Novavax and Hyderabad based Covaxin. Both of these are inactivated vaccines.
- Bharat Biotech’s Covaxin
India’s indigenous vaccine COVAXIN is being developed by Hyderabad-based Bharat Biotech against the novel coronavirus, named Covaxin, together with the Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV), Pune.
According to Bharat Biotech, Covaxin is an inactivated vaccine developed from an Indian strain of the novel coronavirus isolated by NIV and is being made with alum as adjuvant.
- Novavax Vaccine
Novavax vaccine is being developed by US biotechnology company Novavax and is a type of inactivated vaccine. This vaccine is being made by proteins from the coronavirus that cannot replicate in the body and an adjuvant is being used in it to boost the immune response.
Coronavirus Vaccines Being Developed by Modern/New Technology Method (Genetic vaccines/Viral vector vaccines)
Modern vaccines have several categories, but major categories are – Genetic Vaccines and Viral Vector Vaccines.
- Genetic Vaccine
These vaccines provide the host with the genetic material required to build the COVID-19 vaccine. They are also known as mRNA and DNA vaccines. These vaccines contain genetic materials that code for specific proteins (antigens) from a pathogen. The DNA/ mRNA is injected into the body and taken up by human cells, which further synthesize proteins based on the genetic code in the plasmid (mRNA/ DNA) that they have taken up.
In the coronavirus vaccine, these genes code for the S-protein or Spike protein that forms the outer layer of the coronavirus.
- Viral Vector Vaccine
In the viral vector vaccines, they take another virus ( host) and replace its genetic payload with the sequence coding for the antigen of the required virus (SARS-Cov-2). The host virus is used as a vector and these host viruses are attenuated/ weakened so that they cannot cause any illness.
So in technical terms, vector vaccine is a vaccine that uses a chemically weakened virus to transport pieces of the pathogen to stimulate an immune response in the human body. Viruses expressing pathogen proteins are currently being developed as vaccines against these pathogens, based on the same rationale as DNA vaccines.
A lot of viruses are being used as a vector, but most commonly- Adenoviruses (mild cold-causing viruses are used as vectors.)
Coronavirus Vaccines Being Developed With Modern Technology
Some of the frontrunners for the Covid vaccine candidates, using these modern technologies (as they tend to take less time to manufacture), are –
- Moderna, Pfizer & BioNTech
Moderna’s vaccine is an mRNA vaccine- mRNA1273 and Pfizer and BioNTech vaccine- BNT162 are also an mRNA vaccine. Both these vaccines are embedded with a piece of genetic code that trains our bodies to recognize imminent enemy action against the spike protein, present on the surface of the coronavirus.
When the mRNA enters our cells, it begins to spew copies of the coronavirus’ spike protein. That prompts the immune system to churn out antibodies against the coronavirus which originally has the same Spike protein.
2.AstraZeneca & University of Oxford, Johnson &Johnson, Sputnik V are producing Adenovirus vaccines
Both of these vaccines consist of the engineered virus, called adenoviral vectors, which are designed to shuttle a gene from SARS-Cov-2, that causes COVID-19, into our bodies where our cells will read it and make coronavirus spike proteins.
AstraZeneca is using the chimpanzee adenovirus and Johnson & Johnson is using human adenovirus-26. Sputnik V, Russia’s vaccine is also based on the same principle, it is also a human adenoviral vector-based vaccine
Immunogenicity of vaccine
As of now, after several phases of testing, it is being established by different pharmaceutical companies including Moderna, Pfizer & BioNTech, Astrazeneca, that their vaccines have shown efficiency of more than 90% under different circumstances.
However it is important to note that till date there is no mRNA – DNA vaccine that has got approval from the Food and Drug Administration, US, neither any adenoviral vaccine has got the nod. Even as the technology being used to develop these vaccines is 3 decades old, there has been no significant use of it till date, in terms of vaccines.
If any of these vaccine candidates make their way to approval from the FDA, it will be the first of its kind. Be it inactivated vaccine or genetically manufactured vaccine, we need the best and safest vaccine at the end of the day, not the first one.
And the only way to determine any vaccine’s immunogenicity is through rigorous trials under varied circumstances, across several age groups. After trials, a fair amount of time will be required to analyze the data collected from trials for approvals of these vaccines across the world.
Logistics and Distribution of different Vaccines
At this juncture, after understanding various processes of manufacturing a vaccine, we should also comprehend how these can be stored, transported and distributed. Even if we have a fully manufactured vaccine in our hands by early 2021, it is important to have a suitable infrastructure to distribute it amongst masses.
Starting with the logistical requirements of the mRNA vaccine, as per various scientific establishments, it is found that these vaccines need to be stored under extremely cold temperature (-2 to -70 degree celsius) or below to last up to six months. In standard fridges, it has a lifespan of up to 5 days. Even for transportation, airlines are preparing for a global airlift of vaccines while maintaining these temperatures.
Considering an ideal situation, it is certainly an impractical temperature as not all developing countries have enough cold storage units, electricity or infrastructure to use mRNA vaccines for mass distribution. Doctors, offices, pharmacies and state labs in India don’t have freezers.
Coming on to viral vaccines, all viral vaccines must either be stored frozen or kept at low temperatures. If they are not properly stored, they lose potency and do not confer protection against infection.
Earlier at the time of the Pulse Polio campaign, 27, 000 cold storage units were used in India, but are these public distribution units still reliable or perfectly functional or repairable? That’s the big question that needs to be looked into.
However, on the other hand, protein-based vaccines, that are conventional (inactivated vaccines) are easier to store, distribute and do not require extremely low temperatures to be stored. Being familiar with these vaccines earlier as well, we can disseminate them easily. Not just storage, we need enough human resources ( trained people) and equipment to vaccinate the masses, as the COVID-19 vaccines are not oral vaccines, they have to be injected. We also have to make sure that we don’t fall short of syringes etc.
Talking about these challenges for India, Dr Faud Halim (Kolkata Swasthya Sankalp) said, “If we look at the previous experience of how we have used vaccines, trying to control Smallpox and Polio, we have distributed those vaccines free of cost, hence the market forces were not allowed to influence the procurement and distribution of these vaccines, hence they were successfully distributed. If the coronavirus vaccine will be sold, it will not be able to achieve what it is meant for- to create a break in the chain as some will be able to buy it and some will not.”
He added that demand will be another challenge, “We have not placed enough demand for the vaccines, third world countries including India have certainly not asked for enough doses and manufacturing them on a large scale will take a lot of time. There will be a disparity in distribution once we start disseminating the vaccine and if we fall short of it then. After the vaccine arrives, it is important to ensure that we have an adequate number of doses of the vaccine and appropriate infrastructure and manpower to distribute it.”
“The mRNA vaccine as it has a short lifespan and its potency is low, it has to be delivered on a mass scale at the same time, you can’t have a staggered vaccination schedule or patchwork to eliminate the virus from the system.”
Talking about the timeline and schedule of inoculating the vaccine to a common person in India, Dr Faud supported Dr Randeep Guleria’s (AIIMS Director) interpretation and said, “that given the way the Government of India is working at this point of time, a common man will only be able to get the vaccine by 2022, though the sample vaccine may be available in early months of 2021 as claimed by health minister Dr Harshvardhan, it will surely don’t reach the masses that early.”
However, some of the top US and European Union officials have claimed that they are likely to dispense the first few doses of the vaccine by this Christmas. Nevertheless, only time will tell who gets the vaccine and when.
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