The Hindu Explains | Who are the top contenders in the race for a COVID-19 vaccine?

What are the hurdles in the way to stem the march of the SARS-CoV-2 virus?

Updated - November 22, 2020 01:08 pm IST

Published - November 22, 2020 01:30 am IST

Image for representation purpose only.

Image for representation purpose only.

The story so far: Herculean and nearly unparalleled efforts in science over the past few months have yielded at least two COVID-19 vaccines with promise, in a historically short span of time. Global efforts to find a vaccine to stem the march of the SARS-CoV-2 virus seem to be bearing fruit. By November, certain candidates emerged that claimed to offer safe and efficacious action against the virus. Pfizer and Moderna are among the leaders, while progress continues on the Oxford vaccine after a hiatus; China and Russia have claimed successes too.

Who are the top contenders at this stage?

The past two weeks have been brimming with hope after announcements from major pharma companies, Pfizer and Moderna, about over 90% efficacy in their mRNA vaccine trials.

The Hindu Explains | Why is Phase-3 of COVID-19 vaccine trial complicated?

On Saturday, Pfizer and its German partner BioNTech applied to the U.S. drug regulatory authority (Food and Drug Administration, or FDA) seeking emergency use authorisation (EUA) for its COVID-19 vaccine , labelled ‘BNT162b2’. On November 8, Pfizer released preliminary results from 94 people — it had found just over 90% efficacy with its vaccine. In a subsequent announcement later, the company claimed that the vaccine had over 95% efficacy. In all, of over 43,000 volunteers, 170 contracted COVID-19 in Pfizer's trial, and 162 of them had only received the placebo. Two doses of the vaccine were administered.

Moderna followed Pfizer’s initial announcement with one of its own. It claimed that its vaccine was 94.5% effective in a 30,000-participant study in the U.S. The results were based on an initial analysis of 95 cases, of which 90 cases of COVID-19 were recorded in the placebo group, and five cases in the vaccine arm. Moderna also plans to apply for an EUA soon. While reviewing safety aspects, both firms recorded that the majority of adverse events were mild or moderate in severity.

The U.S. FDA had determined a minimum efficacy of 50% for a vaccine candidate. The results revealed so far are higher than what was originally thought possible. Seeking to reassure those with apprehensions about the “incredible speed in vaccine development”, Anthony Fauci, Director, National Institute of Allergy and Infectious Diseases, U.S., said during a White House briefing: “[It] is unprecedented. But it did not compromise the safety of the vaccine or the scientific integrity of the process … we need to put to rest any concept that this was rushed in an inappropriate way. This is really solid.” It is expected that the two companies could produce doses for about 20 million people in the U.S. by December. The first doses will go to people in the high-risk category, including healthcare workers.

Coronavirus | 40 million COVID-19 vaccine doses to be available by the end of the year: White House

Which are the other vaccines in the pipeline?

Oxford University and its partner AstraZeneca are expecting the results of their phase-3 trials by Christmas, and have reportedly seen a good immune response in earlier trials among senior citizens. Adar Poonawalla, CEO of Serum Institute of India, Oxford University’s partner in India, said last week that “the Oxford COVID-19 vaccine should be available for healthcare workers and elderly people by around February 2021 and by April for the general public”. He added that it will be available in the market at ₹1,000 for two necessary doses , depending on the final trial results and regulatory approvals.

Coronavirus | Oxford University COVID-19 vaccine ‘encouraging’ for older age groups: study

China’s CanSino Biologics said it had developed a vaccine based on an adenovirus, in partnership with the Institute of Biology of the Academy of Military Medical Sciences. Claiming that evidence from the phase-2 trial had demonstrated that the vaccine produced a strong immune response, the Chinese military authorised the use of the vaccine as a specially needed drug in June-end, according to media reports. It has since continued with phase-3 trials in other partner countries.

In August, Russian President Vladimir Putin announced the arrival of an indigenous vaccine , reportedly before phase-3 trials. Later, the country clarified that the final approval would depend on the results of the phase-3 trials, to be conducted on about 40,000 volunteers. Russia also reached out to other nations to sign agreements to test its most promising vaccine candidate, Sputnik V, based on two adenoviruses. India joined the trials in October.

The Hindu Explains | What do we know about Russia’s COVID-19 vaccine candidate Sputnik V?

Johnson and Johnson reported that it had started phase-3 vaccine trials to assess the safety and effectiveness in up to 60,000 participants. Some media reports peg the release of this data at the end of this year, or early next.

What are the challenges?

While the biggest challenge is making the vaccine available and affordable to all, there are other hurdles too. Investments to establish massive infrastructure to produce several hundred billion doses will be required. Once that hurdle is crossed, there is the complex logistics of rolling out the vaccine for use. Additionally, with the mRNA vaccine requiring deep cooling, with temperatures several degrees below zero, and two of the top contenders being built on the mRNA platform, elaborate systems of drug delivery and the investment for that should be guaranteed. Otherwise, the vaccines will self-destruct at high temperatures. In countries that do not have a robust cold-chain system , this will be a challenge. While several governments are pre-booking large consignments of doses, the question that remains is how poor and middle-income countries will cope, even as they are offered assistance from agencies such as UNICEF and Gavi, The Vaccine Alliance .

Also read | The storage tale of two vaccines

Meanwhile, efforts to reduce transmission by wearing masks, maintaining physical distance, and frequent hand washing must not suffer, epidemiologists warn.

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