|Year : 2021 | Volume
| Issue : 1 | Page : 1-2
The conundrum of COVID-19 vaccine
Barun K Nayak
PD Hinduja National Hospital and Medical Research Centre, Mumbai, Maharashtra, India
|Date of Submission||17-Mar-2021|
|Date of Decision||19-Mar-2021|
|Date of Acceptance||19-Mar-2021|
|Date of Web Publication||10-Apr-2021|
Barun K Nayak
PD Hinduja National Hospital and Medical Research Centre, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Nayak BK. The conundrum of COVID-19 vaccine. J Clin Ophthalmol Res 2021;9:1-2
It is now more than a year that we have been trying to fight the COVID-19 pandemic, which is caused by SARS-CoV-2, with whatever means we have. Although no one would have ever imagined the impact, this virus has created affecting the entire world negatively. It has presented many challenges to humanity on the whole. It is commendable that people have learned to deal with this situation, both medically and economically, though there still is a long way to go. Many facts about this disease are still unknown to humankind, however, scientists from all over the world have come together and have achieved many milestones. Genome sequencing was deciphered in less than a month paving way for researches in development of vaccines in different countries by various companies at an unimaginable pace.
Historically, none of the vaccines in the past have taken <5 years to develop authentically considering the complexities, efficacy, and side effect issues. Basic data of the SARS-CoV-2 were made available freely to scientists all over the world. The positive out of this situation at such a short notice is the fact that more than 300 vaccine projects were started, out of which more than 50 have reached the clinical trial stage. Some of them have been even granted permission for general public use under the heading of “Emergency Use Authorization” (EUA) considering the urgency due to the havoc created by this pandemic.
How does the vaccine work? Whenever the virus infects the target tissue in the human body, antibodies are produced to neutralize the organism. Simultaneously, it also induces T-cell-mediated reaction producing lymphocytes which attacks the viral-infected cells and destroys it. This provides capability to fight the infection as well as boosts the immunity of the affected person after recovery from the disease. The duration of immunity is variable based on the different organisms. It is important to note that Type 1 T-cell response is beneficial to provide antiviral immunity whereas Type-2 T-cell response is harmful. The role of the vaccine when given to a person is supposed to induce a similar reaction to provide protection, without escalating the disease to a severe form if contracted. The vaccine induces a similar reaction in the body in a milder controlled way so that the human body becomes immune and can deal with the infection in an effective manner without getting seriously affected. The duration of the immunity provided by the vaccine usually lasts for the same period as provided by the active infection itself. This duration of immunity subsequent to COVID-19 infection is unknown as of today.
How is the vaccine developed in the laboratory? Various antigens produced in the organism are given to the human body to set up an immune reaction. In SARS-CoV-2 infection, the most important among many ingredients present in the virus is the binding site of the spike protein which is used to generate immunity. There have been various technologies used for the production of various types of vaccines against SARS-CoV-2.
- Vaccines based on attenuated viruses – Attenuated live viruses, which are not capable of producing the disease, are given to the body to generate immunity against it. Three companies (including Serum Institute of India, Pune) from different countries have taken up projects in this technology, but none of the three vaccines have reached the stage of clinical trials
- Vaccines based on the inactivated virus – Killed viruses are used to generate antigenic response. Bharat Biotech India has developed a vaccine based on this technology which has been named CoVaxin and has also been granted EUA in India, apart from some other countries. In addition to this, five companies from China and one company from Kazakhstan are also trying to make vaccine with similar technology
- Vaccines based on virus proteins – In this type of vaccine, the spike protein and some additional fragments of other relevant proteins are used to generate immunity. More than 15 types of vaccines are in the various stages of clinical trials
- Naked DNA-based vaccine – About six DNA vaccines coded with spike proteins or its fragments have entered clinical trials. The vaccine developed by Zydus Cadila from India, falls in this category
- Messenger RNA (mRNA)-based vaccines – Moderna US vaccines and Pfizer US–BioNTech are already approved for EUA, in the US and European countries. The vaccine developed by Oxford University UK in the form of an inhaler, is also in the final phases of clinical trial. One major problem with this group of vaccine is that it has to be kept in an environment of −30°C to−80°C
- Vaccine based on viral vector – vaccine developed by AstraZeneca Sweden-UK manufactured by Serum Institute of India, Pune, named Covishield has been granted EUA in many countries, including India. In this vaccine, chimpanzee adenovirus is used as the vector for carrying mRNA for the spike protein. Another vaccines in the same category are in the process of development by Bharat Biotech-Washington University by India-US, Sputnik V developed by Gamaleya Research Institute, Russia, and Ad26COVs1 developed by Johnson and Johnson, USA. Some of them have been granted EUA in the USA, under the same category.
Why so much rush in granting the permission? It is a horrifying fact that in a short period of just over 1 year, more than 122 million people have been affected and more than 2.7 million deaths have occurred all over the world because of this pandemic. The urgency to handle the situation has pushed people to take many shortcuts in the development of vaccines including the permission to use in public. It has been granted EUA in the US, without establishing the duration of the immunity produced by vaccination and establishment of long-term side effect, if any. Although the initial data suggest that the efficacy of the vaccine produced by Pfizer-BioNTech Moderna and Sputnik V developed in Russia, has an efficacy of more than 90% whereas Covishield developed by Serum Institute of India is 62%. It was noticed that the efficacy of the vaccine rose up to 90% when the dose administered in the first round was half with a full dose in the second administration after 4 weeks. This was noticed by Oxford University AstraZeneca trial in the UK. Another interesting finding observed in a small subset was that improved efficacy was observed when the second dose was repeated after 12 weeks as compared to the usual recommendation of 4 weeks.
What is the role of India on the international scene? A major challenge is the production and availability of the COVID vaccine to the entire world including the countries with low socioeconomic conditions. We always underestimate the strength of India, although throughout the world India is considered as a major hub for pharma industry, specializing in providing good quality medicines at a reasonable price. More than 60% of all types of vaccines are provided to the world by India, today. The scenario is no different in relation to COVID-19 vaccine. Already, India has supplied the vaccine to many countries, apart from initiating the largest vaccination drive for its own population. With the research going on and future stepping up of vaccine production, no other country can match India's capacity.
A general perception which I notice not only in the general public but surprisingly also among doctor's community is that as the vaccine has been rolled out, everything is under control and safe. However, we should not forget that we are dealing with a RNA virus which has characteristics of mutating rapidly. We also do not know how the mutant strain will respond to the vaccine. As of now, we understand that none of the vaccines developed so far are ideal and suitable in all circumstances in various populations. We will have to wait for the development of second and third generations of vaccines and will also have to learn the fact that which vaccines can be mixed and matched to suit the various populations in different countries. The interval of administration of booster dose after the initial two doses of immunization, remains to be established. It is also to be seen whether the vaccine will be equally effective to the most fragile sections such as old persons, persons from low socioeconomic conditions, and persons with autoimmune diseases with some comorbidities. Till then, no relaxation should be entertained in (i) wearing masks, (ii) social distancing, and (iii) proper sanitization measures and safety rules.
| References|| |
Forni G, Mantovani A. COVID-19 vaccines: where we stand and challenges ahead. Cell Death Differ 2021;28:626-39.
[Table 1], [Table 2], [Table 3]