By Prof Upendra Kaul
VACCINATION, is a simple, safe, and effective way of protecting people against harmful diseases, before they come into contact with them. We now have vaccines to prevent more than 20 life-threatening diseases, helping people of all ages live longer, healthier lives. Immunization currently prevents 2-3 million deaths worldwide, every year from diseases like diphtheria, tetanus, whooping cough (pertussis), influenza and measles etc. It makes the body’s systems immune to get infections against which vaccination has been done.
The term vaccine , is related to Edward Jenner to denote cowpox ,Variolae vaccinae (smallpox of the cow), which he discovered in 1798 and used for small pox prevention. In 1881, to honour Jenner, Louis Pasteur proposed that the term should be extended to cover the new protective inoculations then being developed and the term thus stayed.
The vaccine development programs are complex and have several stages; Exploratory stage, Pre-clinical stage, Clinical development, Regulatory review and approval, Manufacturing and Quality control. Clinical development is a three-phase process. During Phase I, small groups of people receive the trial vaccine. In Phase II, the clinical study is expanded and vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In Phase III, the vaccine is given to thousands of people and tested for efficacy and safety. Many vaccines undergo Phase IV formal, ongoing studies after the vaccine is approved and licensed (post marketing surveillance).
What about COVID 19? There are around 100 vaccines being developed against SARS-CoV-2 by research teams in companies and universities across the world. Researchers are trying different technologies, some of which haven’t been used in a licensed vaccine before.
All vaccines aim to expose the body to an antigen that won’t cause disease, but will provoke an immune response that can block or kill the virus if a person becomes infected. The four groups 1. Virus- Inactivated or weakened, 2. Viral Vector- replicating and Non-Replicating. 3. Nucleic Acid based- DNA or RNA. 4.Protein based- Protein subunit and Virus like particles.
The first vaccine to be launched for human use has been the SPUTNIK vaccine made by Gamaleya Centre, Russia. They have been working on adenoviral vector-based vaccines since the 1980s, and now lead the world in developing these types of vaccines. During the vaccine creation process, a gene with the code of a coronavirus S (spike) protein is inserted into an adenoviral vector. This inserted component is safe for the human body, but still helps the immune system to react and produce the antibodies that protect us from infection. The vaccine has criticism attached to it because of abbreviating the phases and not publishing the protocol. A few days back they announced to the press that it has a 92% success based upon an interim analysis of 20 COVID-19 cases identified among trial participants. These numbers according to experts are too few. They have also approached Indian companies for joint collaborations for mass scale production of this vaccine. Dr Reddy’s Laboratories Ltd. plans to distribute the Russian vaccine in India after conducting final-stage human trials.
Zydus Cadila of India is working with 2 COVID vaccines, one using DNA and the other using Replicating Viral Vector. Both are in Phase II at present. The Serum Institute of India vaccine based upon live attenuated virus is also in early stages. They are partnering with Codagenix vaccine which is in pre-clinical trials and their Novavax candidate is only a few months behind the Astra-Zenica Oxford vaccine. They plan to complete their trials by March 2021 and if efficacy proven have the capacity to produce up to 100 million doses a year initially.
The other very talked about vaccine is the Oxford vaccine which had in their preliminary report of its Phase 1 and 2 published in July shown an acceptable safety profile, and homologous boosting increased antibody responses. The vaccine was the chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19). These results, together with the induction of both humoral and cellular immune responses, support a large-scale evaluation of this vaccine in an ongoing phase 3 program involving several thousand subjects assessing safety and efficacy. In another publication very recently, they have shown that it appears to be better tolerated in older adults than in younger adults and has similar immunogenicity across all age groups after a boost dose. Further assessment of the efficacy of this vaccine is being done in all age groups and individuals with comorbidities. Serum Institute of India one of the largest manufacturers of vaccines is also looking at collaboration with Astra Zenica for bulk manufacture once Phase 3 is done and efficacy documented, the safety has already been established. The vaccine does not have very fastidious requirements for storing and transporting beyond what is available with us.
The latest amazing news has been the announcement by Pfizer, USA and BioNTECH , Germany after conducting the final efficacy analysis in their ongoing Phase 3 study of the mRNA-based COVID-19 vaccine, BNT162b2 . It seems to have met all the study’s primary efficacy endpoints. Analysis of the data indicates a vaccine efficacy rate of 95% in participants without prior SARS-CoV-2 infection (first primary objective) and also in participants with and without prior SARS-CoV-2 infection (second primary objective. The first primary objective analysis report is based on Efficacy which was consistent across age, gender, race and ethnicity demographics. The observed efficacy in adults over 65 years of age was over 94%. No safety issues have been reported to the US FDA which is closely monitoring the program. The vaccine trial is being done at 150 clinical trials sites in the United States, Germany, Turkey, South Africa, Brazil and Argentina. The trial will continue to collect efficacy and safety data in participants for an additional two years. The down side of this vaccine is that it needs very stringent conditions for storing and transporting which also have been developed. The companies have developed specially designed, temperature-controlled thermal shippers utilizing dry ice to maintain temperature conditions of -70°C±10°C. They can be used be as temporary storage units for 15 days by refilling with dry ice. Each shipper contains a GPS-enabled thermal sensor to track the location and temperature of each vaccine shipment across their pre-set routes leveraging Pfizer’s broad distribution network. Once the efficacy study is completed it will be published in a peer reviewed journal to show the entire safety and efficacy data.
The vaccine is expected to be launched by the end of December 2020, once the data is approved for emergency use in high risk populations. Based on current projections, the companies expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses by the end of 2021. This amazingly effective vaccine is not likely to reach populations of Asian countries for the present.
Our hope is therefore on the OXFORD vaccine from Astra Zenica and their collaborations with our mass producers of the vaccine. This hopefully will be supplemented with the other vaccines coming up from companies like Zydus Cadila. The time frame of availability could be by mid-2021.
With the total number of cases in India of COVID-19, mounting around 9,050,598, on 21 November, the country’s death toll has mounted to 132,726. On an average we are seeing 50,000 new cases with around 550 deaths a day. The status of the UT of Jammu and Kashmir has been improving slowly with around 650 new cases per day with 4 to 5 deaths. Fortunately, the mortality in our part of the world has been around 1.5 %, which is much lower than what was reported in Europe and America.
This pandemic has infected 57 million patients with 1.37 million deaths so far. The need for preventive measures like self-distancing, hand hygiene and wearing of masks cannot be under emphasized. The attention has now changed to working feverishly for an effective vaccine which should be available for our masses. We really need an early breakthrough from science, technology and not just a political rhetoric. Let us be optimistic, that year 2021 will bring in the much-awaited vaccine.
- The Author is a Cardiologist, recipient of Padmashiri and Dr B C Roy Award
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