COVID 19 Vaccine: Prospects & Apprehensions
In the quest for finding an effective vaccine at the earliest to control the devastating COVID 19 pandemic, there has been an undeclared competition among different agencies and pharmaceutical companies to have the first approval for such a vaccine. After obtaining promising results from clinical trials conducted so far, vaccine developers are now trying to garner ‘emergency use’ approvals, which necessarily would mean evading a number of important regulatory steps in the normal process of approval of a new vaccine to ensure safety and accuracy. Scientists are, therefore, worried that this kind of early deployment could eventually compromise the needed efficacy of the vaccine that may jeopardize the protection induced by such a vaccine in millions of recipients.
The New York based company, Pfizer and Germany based BioNTech have already submitted an application on 20 November, 2020 to the US Food and Drug Administration (FDA) for an Emergency Use Authorization (EUA). Another front runner among the COVID 19 vaccine developers, Moderna, based in Cambridge, Massachusetts, declared that it would also apply for a EUA in the coming weeks. The FDA announced that its vaccine advisory committee will meet on 10 December, 2020 to assess the data pertaining to clinical trials submitted by the companies and decide whether the vaccines are safe and effective enough for its approval for restricted use.
However, a number of scientists have raised their voices of concern regarding the appropriateness of such emergency use approvals. As the vaccines have been tested for only a couple of months, in their opinion, it is too early to know how long they will be effective for. As the phase III clinical trial is being carried out as double-blinded trial, the volunteers receiving a placebo initially, would jump over to the vaccine group soon after unblinding of the trial by the developers. This is also expected to have significant influence on the understanding as to the long-term efficacy and safety of the vaccine.
According to Eng Eong Ooi, an infectious-disease researcher at Duke–NUS Medical School in Singapore, “Any vaccine approved, even if only for emergency use, will change the landscape of how vaccines get into the market”. Consequent to a EUA granted to some company for a COVID 19 vaccine, the process of getting similar approval in future would become more complicated. Companies seeking to start a new trial will have to first show that their vaccines are better than those granted emergency approval, and as a result new trials would become more challenging and expensive.
So far, the developers of three potential COVID-19 vaccines have released their preliminary data from Phase III trials – Pfizer, Moderna and AstraZeneca. Additionally, many other vaccine candidates are now in Phase III trials including the Indian vaccine, Covaxin, being developed indigenously by Bharat Biotech in collaboration with ICMR. The phase III clinical trial of Covaxin has already been started with an aim of recruiting more than 28,000 volunteers in 21 institutes across the country.
Although the Pfizer- BioNTech COVID vaccine has shown more than 90% efficacy in the phase III trial involving 30,000 volunteers and is the front runner in the process of getting a EUA from FDA, there is uncertainty over availability of this vaccine in India in the near future. Pfizer has revealed that it is talking to the Government of India to include the vaccine as a part of its COVID-19 vaccination efforts. An important concern about this vaccine is that, being an mRNA based vaccine, it requires specialized cold storage facilities, as it is needed to be stored at -70°C for maximum efficacy, which could be quite challenging to ensure throughout the supply chain in this country and may substantially increase its cost.
Another front runner, Moderna’s COVID 19 vaccine is also based on a similar mRNA platform as that of Pfizer-BioNTech. This vaccine has also showed more than 92% efficacy in the phase III clinical trials. However, the probability of large scale availability of this vaccine for mass immunization in India is again very low owing to its requirement of maintenance of cold chain at -20°C.
Another front-runner among COVID vaccines, AZD1222, being developed by AstraZeneca and University of Oxford is based on a chimpanzee adenovirus called ChAdOx1 as a vector. Unlike the previously named vaccines, this vaccine does not require deep freezing for its storage and can be stored at 4-7°C being an inactivated one. It has already been announced that the vaccine would be distributed through Serum Institute of India (SII), the largest vaccine producer in the world. As per media reports, SII has already produced four crore doses of the vaccine that would be adequate for two crore people as it is to be given in two doses. Serum Institute has offered the vaccine at $3 (equivalent to around Rs. 225.00) per dose. The vaccine is expected to be available early next year.
Russia’s Sputnik V is the world’s first registered vaccine that is a human adenoviral vector-based vaccine claimed to be more than 95% effective. It has been produced in a lyophilized (dry) form that can be stored at 2 to 8°C. The vaccine has been developed by Gamaleya Research Institute of Russia. However, the rapidity at which this vaccine was approved, some scientists have expressed apprehensions that safety of the vaccine might have been compromised in the process.
COVAXIN, the Indian vaccine for which Phase III trial has recently been started, also is a whole virion inactivated vaccine, and therefore would not require storage at a very low temperature. It would require storage at 2-8°C or higher. Being an indigenously developed vaccine, India has high expectations on the results of the ongoing phase III clinical trial in respect of efficacy of the vaccine, as once it is proven effective and safe, it wouldn’t be difficult for the Indian Government to ensure rapid massive scale production so as to make it available to the Indian public at a much lesser rate or even at free of cost.
Although the currently available data have revealed a promising future for at least a few upcoming COVID 19 vaccines, many questions are yet to be answered and researchers feel that more and more research efforts are needed to know them better. It is not yet known how well the vaccines would work in high risk groups, including older individuals, people with obesity and those with co-morbidities like diabetes. It is not clear how well the vaccines could protect against severe forms of COVID-19. It is also not clear as to whether the vaccinated individuals would continue to transmit the virus to others and hence complicate diagnosis of infections acquired by a susceptible individual. The duration of immunity to be conferred by the COVID 19 vaccines is also not yet clearly known, although some reports have said that it would provide immunity for sufficient duration – from months to years or even decades. However, such claims are to be validated by experimental data in due course of time.
Let’s hope that we would soon find satisfactory and convincing answers to all these unanswered questions, and all controversies regarding the safety and efficacy of the vaccines would eventually end forever. After all, we are all waiting to see the humanity to once again win over the menace of this devastating pandemic as it did a number of times earlier in the history.