Within days, American pharma giant Pfizer has made two big positive announcements on Covid-19 vaccine developments. After declaring 90 per cent effectiveness of the vaccine in the first release on the third stage of the clinical trial of its Covid-19 vaccine, Pfizer has now said its vaccine candidate has achieved 95 per cent effectiveness.
The company, which is developing the Covid-19 vaccine in partnership with German drugmaker BioNTech SE, said there has been no serious safety concerns related to the vaccine.
Pfizer said, “The safety milestone required by the US FDA (Food and Drug Administration) for Emergency Use Authorization (EUA) has been achievedWithin days, we plan to submit a request to the US FDA for an EUA based on the totality of safety and efficacy data collected, as well as manufacturing data relating to the quality and consistency of the vaccine candidate.”
So, when will one get the Covid-19 vaccine?
This is a tough question to answer. Pfizer’s results are positive enough to raise high hopes for an early arrival of a Covid-19 vaccine. But there are other aspects that would warrant patience.
Pfizer has released the results of only 170 cases out of nearly 40,000 volunteers, who were inoculated with the vaccine candidate and placebo. The authorisation process in the US requires safety data of at least two months of trial. Pfizer’s vaccine candidate has reached that stage but it will not be guaranteed to get an early approval from the American authorities.
Vaccine development is a tedious process passing through certain stages. Briefly speaking, every vaccine has to pass through five broad stages before a normal individual can use it.
Pre-clinical trial stage
This involves exploratory study and intensive research designed to find a natural or synthetic antigen that mimics the actual pathogen — in the case of Covid-19, it is SARS-CoV-2 — and develop it into an administrable drug.
Clinical trial phases 1 and 2
These two phases can be run together or separately. They are conducted to see if the vaccine candidate is safe or not, and also to determine the right doses. The sample size is small, usually less than 100. If these stages are successful, a bigger clinical trial is undertaken.
Phase 3 of trial
This is the final stage of the trial wherein it is determined how effective the vaccine candidate is. Pfizer’s vaccine candidate is currently under this phase of the clinical trial. Here, the sample size is big, usually involving thousands of people.
Pfizer’s own website says it conducts trials in four stages. After the phase-3 trials, it conducts the fourth-phase trial on an even bigger sample size even if it has been granted authorisation for use.
This is the fourth broad stage of vaccine development. After the completion of phase-3 clinical trials, the drugmakers apply for approval from regulatory authorities. The regulatory authorities conduct inspection and investigation into the claims made by the drugmakers and if they are satisfied, they award license for manufacturing of the vaccine.
In its latest release, Pfizer has talked about applying to the FDA in the US for this licensure from the authorities.
Manufacturing and quality control
Like the FDA in the US, in every country, the regulatory authorities continue to monitor manufacturing of drugs including vaccines to ensure safety. In case of many vaccines, the phase-4 of clinical trials is undertaken when the vaccine is being manufactured and sold for authorised use by normal individuals.
The fourth phase of trials is undertaken to see whether the vaccine stays safe in the long run for the world. No Covid-19 vaccine candidate has reached this stage.
When can we expect Pfizer’s Covid-19 vaccine in India?
A fixed timeline for the arrival of Pfizer’s or any other developer’s Covid-19 vaccine candidate cannot be predicted. Assuming that Pfizer’s Covid-19 vaccine candidates gets the emergency authorisation in the US, it will take a couple of months for the Americans to get it.
In India, there is an additional problem — involving technical capability. Pfizer’s vaccine requires storage at minus 70 degree Celsius. There is not too much storage capacity in India for such requirements.
Niti Aayog member (Health) VK Paul, who heads the National Task Force on Covid-19, has said the government is looking at the possibility for procurement and distribution of Pfizer’s Covid-19 vaccine if it gets regulatory approvals but made it clear that there cannot be sufficient doses of that vaccine as required for the India’s population size.
Moreover, whatever deals that Pfizer has struck with countries such as the US, the UK, Japan and the European Union, it needs to send hundreds of millions of doses to these countries. India can expect its first batch only after that from the Pfizer.
And, more importantly, Pfizer has not conducted human trials for its vaccine in India. The regulatory requirements in India warrant that a vaccine undergoes local trials before it can receive approval. Pfizer may have to find a local partner to conduct such trials or does the same on its own.
Pfizer’s as well as Moderna’s vaccine candidates are being developed using mRNA (messenger ribonucleic acid) technology. No mRNA vaccine has been approved till date. India’s focus has mainly been on five other Covid-19 vaccine candidates. These are being tested by the Serum Institute of India, the Bharat Biotech, Zydus Cadila, Dr Reddy’s Lab and Biological E.