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Why we shouldn’t have unrealistic expectations regarding COVID-19 vaccines

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Vaccines can take a long time to be developed, longer than most pharmaceutical, medicinal or drug products.

Why we shouldn’t have unrealistic expectations regarding COVID-19 vaccines
Among pharmaceutical, medicinal and drug products, vaccines are by far the most complex. They are also life-saving. In times of devastating disease outbreaks such as the COVID-19 pandemic, it is not uncommon to foster hopes that an effective vaccine, a magic bullet, could somehow be quickly made and administered to people. Unfortunately, reality can be very different because vaccines can take a long time to be developed, longer than most pharmaceutical, medicinal or drug products.
At the core of this complexity lies the basic idea behind a vaccine. Most medicines are prescribed to patients once they fall sick. Someone who is ill takes a tablet or an injection, and hopefully, the illness goes away. Vaccines, on the other hand, are given to perfectly healthy people, including children. The purpose is to protect a healthy individual from falling sick through vaccination when the disease strikes.
Designing a vaccine
This means, unlike pharmaceutical medicines whose side-effects can be accepted because the patient is already sick, vaccines require very clean safety profiles because they are administered to healthy people. The second difference is the scale. Most vaccines are administered to millions upon millions of people from all ages, classes, socio-economic structures and gender. Therefore, even a small adverse effect, seen in a small subset of people can sometimes become unacceptable.
To add to this complexity lies the composition of vaccines. Sometimes, this composition can be crude mixtures of viral or bacterial components, formulated to invoke a quick, strong and durable immune response against the disease. The process to manufacture such vaccine components can often be tedious and expensive. In some cases, special factories that can handle the biosafety hazards of vaccine manufacture have to be specially custom built. All these things take time. And a lot of money.
To cite an example, the recent Rotavirus vaccine that was discovered, tested and produced in India took almost three decades from the initial concept to final product availability. Many crores of rupees were invested to make the vaccine a reality. Indian scientists and engineers collaborated extensively with medical research groups abroad and only then could success be achieved.
We certainly hope in the current pandemic, things can move much faster and they certainly will. The scale at which this pandemic has affected the world is unprecedented. Not surprisingly, governments and private enterprises have allotted a huge amount of resources and expertise to develop an effective coronavirus vaccine as quickly as possible.
We should not forget, that prior to December 2019, the world had never seen what we now call 2019-nCoV, the new coronavirus. All around the world, scientists have worked furiously to learn more about the virus and decipher its secrets. But 5-6 months is hardly enough time to learn everything we need to know to make a safe vaccine. Once scientists have a general idea about the virus, they first have to “design” a vaccine. This can take all shapes and forms from using crude inactivated viruses to DNA or RNA or portions of viral proteins. But still, the design piece can be finished relatively quickly.
From animals to humans—The many stages of trials
Next, these vaccine formulations have to be tested in animals to check if they actually work. This is done in laboratory animals such as mice, rats or monkeys. Once a protective “signal” is found, then the vaccine needs to be scaled up and tested in humans using staged trials. This testing and scale-up can take from a few months, up to a year. In the initial stage—Phase I—the safety of the vaccine is tested in healthy adults, usually in small groups of 50-100. Because of the small size of the human trial, it can be accomplished within 3-6 months.
Only if the vaccine is found safe, then it is advanced to the next stage—Phase II—where a larger group of subjects, typically 2000-3000 are tested for efficacy, the question whether the vaccine produces a signal in humans. This stage can take up to a year, sometimes 18 months to finish. Again, only if a positive signal has been observed without any serious side effects, the vaccine is advanced to the next and final stage of clinical testing—Phase III.
Here, very large numbers of subjects—10,000-50,000—across the target population representing multiple geographies, racial, demographic and socio-economic segments have to be tested. This is where the performance of the vaccine is scientifically measured against a placebo while a detailed review of vaccine-related adverse events is carried out. Because of the large size and complexity, the final stage is often the longest, sometimes taking 2-3 years to finish.
And only when the vaccine has been conclusively proven to be effective with a clean safety profile, it is presented to the regulators for licensure. All this while, large factories to mass-produce the vaccine, if it is successful, is commissioned and readied. Together, the clinical testing and large-scale vaccine manufacture can prove to be a logistical challenge for most organisations, and only the experienced ones can manage things successfully. Combined, it can take 4-5 years at the very least to have a finished product, and that too if all goes right the first time.
The reason for optimism
This is the scenario, the foggy lens, through which we need to view COVID-19 vaccine development. There is reason to be optimistic as so much is being done across all levels to make it happen. As we speak, more than 5 different vaccines are in early to mid-stages of human testing in Phase I/II clinical trials. Among them are candidates being developed by universities such as Oxford as well as companies like Moderna, CanSino, Sinopharm and Pfizer.
If successful, two billion doses of the Oxford vaccine which is currently in Phase II/III testing will be made available with the help of $750 million funding from the Bill and Melinda Gates Foundation. The US Biomedical Advanced Research and Development Authority (BARDA) has committed $483 million to support Moderna’s RNA vaccine that showed promise in early Phase I clinical trials. BARDA also awarded $1 billion to AstraZeneca, Oxford’s partner in developing coronavirus vaccine.
Pfizer has committed $500 million to develop new technologies to rapidly develop their vaccines. By any account, these are staggering numbers. And yet, despite all the promise, the inherent complexities of vaccine development cannot be ignored. Of the many approaches being followed, a few will definitely succeed. But whether they do so in the time frame most people expect, remains questionable.
—Dr Davinder Gill is a vaccine expert and former CEO of Hilleman Labs. The views expressed are personal
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