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The World Has a Safe and Effective COVID-19 Vaccine – but Challenges Remain

The World Has a Safe and Effective COVID-19 Vaccine – but Challenges Remain

Photo: Karolina Grabowska/Pexels.

The COVID-19 pandemic has changed many lives in ways that were hard to imagine at the year’s beginning. And as we near the year’s end, let’s spend a moment catching up to the science of the pandemic.

It’s marvellous that for the first time in human history, we have developed safe and effective vaccines within a year of the emergence of a novel virus. Yet a safe and effective vaccine alone is a means to an end – not the end in itself.

On December 3, the UK became the first Western country to authorise a vaccine against COVID-19, and started vaccinating elderly people shortly after. The rapidity of the approval process drew some criticism, including from notable US scientist Dr Anthony Fauci. But Dr Fauci later apologised, and clarified that his comments were meant more to highlight the differences between the approach in the US and the UK. Shortly after, Canada became the second Western country to perform the same feat.

After a group of independent experts who advise the US Food and Drug Administration held a public meeting on December 10, the FDA issued an emergency use authorisation for Pfizer’s COVID-19 vaccine a day later. And a week later, US regulators authorised a second vaccine, developed by Moderna and the US National Institutes of Health (NIH), against COVID-19.

Some other countries, including China, have reportedly started vaccinating hundreds of thousands of people, although it isn’t clear if these vaccine candidates have successfully completed their respective phase 3 clinical trials.

Accelerated development, but safety first

It’s a cliché that drug development takes around 10 years and more than a billion dollars – and it’s also a fact. So it’s only to be expected that many of us have been nervous to anxious about the rapidity with which scientists have developed vaccines against COVID-19.

At the heart of the Pfizer/BioNTech and Moderna vaccines’ accelerated development timeline is the mRNA technology, which allowed designing at unprecedented speeds. In a recent interview, the cofounder of BioNTech Uğur Şahin said that he had designed the vaccine construct in a few hours on a single day. The company spent the rest of the time testing the vaccine – in preclinical trials followed by several phases of human clinical trials.

Global regulators’ final verdict on such vaccine candidates’ safety and efficacy follows high standards. For example, the Pfizer/BioNTech candidate was tested among more than 40,000 people in randomised, double-blind, placebo-controlled trials – the gold standard of drug-testing. Pfizer and BioNTech have since published data from their trials in a medical journal.

At the time of publication, there had been 170 COVID-19 cases among the 40,000+ trial participants. Only eight had been reported from the group that received the vaccines, versus 162 in the group that received a placebo, resulting in 95% efficacy. The vaccine also reportedly, and substantially, reduced the chances of developing severe COVID-19 among trial participants. In the trials, researchers recorded 10 severe cases – nine in the placebo group and one in the vaccinated group. The data also indicated that vaccine efficacy was consistent among the elderly.

Also read: How Do Scientists Calculate Vaccine Efficacy?

The Moderna/NIH vaccine candidate also reportedly had a high efficacy – more than 94% – in randomised controlled trials with 30,000 participants. According to the interim data, 30 cases of severe-COVID in the NIH/Moderna trial all happened in the placebo group, allowing Moderna to claim 100% efficacy against severe COVID-19. (Note: The data from the trial is yet to be be published in a journal, which limits our takeaways.)

While side-effects are common in any trial of this size, four serious adverse events were judged to be related to the vaccine but which independent experts also deemed to be transient. As for long-term side-effects: it’s true that the data thus far spans a couple of months and there may be new side-effects in some groups of people as a vaccine is rolled out to millions. But given how vaccines work, most adverse events could be expected to occur within a short time after administration and are unlikely to happen months later.

In addition, it’s reasonable to expect that when the independent panel of experts convened to advise the FDA, they would have accounted for all of these possibilities.

And from a public health perspective, it’s crucial that we trust the judgement of regulators as long as the process has been transparent.

10 years to 10 months

Pfizer’s and Moderna’s rapid production of vaccine candidates was enabled by mRNA technology. Indeed, these are the first-ever mRNA vaccines to be authorised for human use – although they aren’t the first mRNA drugs to have been approved for sale. The FDA approved another drug in 2016 called Spinraza that is based on the same technology and which has since helped thousands of infants with spinal muscular atrophy. So it’s important to view this technology against the backdrop of a successful precedent.

This said, the underlying science itself dates to the 1990s, when researchers at the University of Wisconsin demonstrated that mice injected with external mRNA could affect the translation of specific proteins in cells. Since then, the field of mRNA vaccines has blossomed, supported by both public and private funds.

Some 30 years have lapsed between the original experiment in mice and the Pfizer/BioNTech vaccine candidate’s authorisation. So effectively it’s a branch of science that has been honed for three decades.

The real power of the mRNA technology comes from its simplicity. To develop a new vaccine against an unknown disease, all you need to know in principle today is the virus’s genetic sequence. Chinese scientists had provided this sequence of the novel coronavirus by January 2020 itself. The clinical trials’ read-outs were also hastened with thanks in part to the trials’ large sizes as well as the unfortunately high infection rates in the US. (As a result of the latter, ‘enough’ trial participants had COVID-19.)

Pfizer’s and Moderna’s successes have shown that mRNA technology is a promising approach for vaccine development. It allows an agile and accelerated response to emerging infectious diseases – and could even be key to address threats from new mutations to SARS-CoV-2, should they fail to respond to existing vaccines.

Challenges remain

It’s great news that we have at least one vaccine now that experts have deemed to be effective and safe after rigorous review. But until this vaccine reaches billions of people around the world, including in India, it will be of little use.

The greatest challenge associated with the Pfizer/BioNTech vaccine is that it needs to be stored at -70º C, which can be difficult to achieve in many countries. At the same time, scientists are also testing improved formulations that may allow storage at higher temperatures.

Then there is the scalability. One of the other leading vaccine candidates – developed by AstraZeneca and the University of Oxford – recently reported positive interim results from its candidate’s phase 3 clinical trials. The key advantage of this vaccine candidate is that it can be stored and transported at 4º-8º C. And thanks to AstraZeneca’s collaboration with the Serum Institute of India – the world’s largest vaccine-maker by volume – this candidate is highly scalable. Serum Institute has already said it will produce up to 100 million doses a month.

Pfizer currently doesn’t appear to have a manufacturing partner in India, although it has already filed for ’emergency use authorisation’ in India.

Also read: Pfizer Vaccine’s Price May Be Throwing off Indian Government, Report Says

As for India – the country’s greatest challenge now will be to approve a safe vaccine as soon as the requisite data becomes available, and in a transparent manner that instils, instead of abuses, public confidence.

Richer countries have already pre-ordered hundreds of millions of doses of various vaccines – while the governments of the US, the UK and Russia have already started inoculating their population. At the time of writing this article, it was unclear if India had sealed any formal purchase agreements with any vaccine-maker.

But on the bright side, many more vaccines are still in the pipeline. The Oxford vaccine itself is set to receive a regulatory decision in Britain in the next few weeks. Vaccinating a substantial proportion of India’s population will present a logistical and operational challenge that requires careful planning. The Government of India has reportedly said that it expects to begin vaccination in January, starting with 300 million front-line workers, elderly people and vulnerable people.

For now, science appears to be done. Our focus should shift to delivering the vaccine to the people who need them – which, as far as the pandemic is concerned, is the end in itself.

Souro Chowdhury is a President’s PhD Scholar in the department of chemistry at the Imperial College London.

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