Covid Vaccine- A Light at the end of the tunnel or a tantalizing wait?

Good news in battalions? The Pfizer vaccine will be suitable for some places whereas the Moderna vaccine may be a better fit for other regions.

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Paraphrasing what the famous English bard said long ago, in the context of the Covid-19 pandemic, we may perhaps say, "when happy news come, they come not single spies, but in battalions."On November 9, 2020, the American pharmaceutical giant Pfizer and its German partner BioNTech announced in a press release that their vaccine is 90 per cent effective-that is, 9 out of 10 people who participated in phase 3 trials of the Pfizer vaccine were effectively protected from infections with the coronavirus. It was indeed a very heartening development.  This was followed by the announcement of Moderna Inc. on November 16 that its vaccine candidate is even better, with 94.5 effectiveness.

On November 18, 2020, Pfizer revised its claim, saying its vaccine candidate has been shown to be 95% effective and that it also protects elderly persons from SARS-CoV-2 infection. The company now asserts that its phase 3 trial is completed and has already started the process of seeking emergency use approval (EUA) of its vaccine by the US FDA.

Meanwhile, Russia's Sputnik V vaccine has purportedly shown 92 per cent effectiveness. The Oxford/AstraZeneca vaccine is likely to have preliminary data of its phase-3 trials before Christmas eve. All these developments are beside the 4-5 Chinese vaccine candidates that claim to close in on the finishing line of the vaccine race (in fact, a few Chinese vaccine candidates have been already used to vaccinate people even before the completion of phase-3 trials).

Has the beginning of the end of the Covid-19 pandemic arrived? Despite the hopeful developments on the vaccine front, we cannot yet give an affirmative answer.

Pfizer versus Moderna vaccines

Both these vaccines are based on the mRNA platform. No vaccine based on this technology has been developed so far. The effectiveness of both the vaccines indicates the promise of this untried platform. But many questions remain before deciding if any of these or both these vaccines will lead to the end of the current pandemic.

As far as India (and Manipur) is concerned, the Pfizer vaccine seems to be out of the reckoning. Why? First, the storage temperature. The Pfizer vaccine needs to be kept at -700C and cold chains need to be created all along the way from vaccine manufacturing plants to delivery centres. How many small towns and interior villages in India or Africa can afford such cold chains of ultra-cold freezers? Second, nearly 70-80 per cent of the Pfizer vaccine has been already purchased by a few rich countries e.g. US, UK, Japan, and the EU. Third, Pfizer and other RNA vaccines will be very costly for poor countries like India.

Let's now look at the Moderna vaccine. The company announced that its vaccine can be stored at 2-80C for 30 days without losing efficacy (though many reports say that this vaccine must be kept at -200C). So, Moderna vaccine may be preserved in a normal refrigerator or cooler filled with ice. Therefore, it may be more amenable to mass distribution in rural areas and low-income countries.

The reason why Moderna vaccine is more robust than the Pfizer counterpart is due to the novel nanoparticle technology, the structural backbone that delivers the mRNA molecule carrying the genetic instructions for making SARS-CoV-2 spike and other proteins into human cells so that our body can raise antibodies and elicit activated T cells that fight the coronavirus, according to Dr Aliasger K. Salem, University of Iowa.

However, it's too early to say who will be the ultimate winner. One critical factor is how the vaccines will perform in the varying demographics of different countries.

Unanswered questions

For all the vaccines nearing the finishing line, many questions remain still unanswered. For example, how lasting will be the immunity generated by the vaccine? Will the SARS-CoV-2 virus mutate in the near future? How much percentage of recovered patients has the risk of re-infection with the coronavirus? How many doses of the vaccine will be needed (many candidates are two-shot vaccines) and will there be need for booster shots? If the virus mutates, will there be need for new versions of the vaccine every year, just like the case of the flu vaccine?

Another problem also remains to be addressed. That of side effects or safety of the vaccine. 10 per cent of people in Moderna's data reported significant side effects including fatigue and myalgia (muscle aches), according to Dr Peter Doshi, University of Maryland. Moreover, both Pfizer's and Moderna's announcements come in the form or press releases and not through peer-reviewed articles. Some side effects are so rare that they will manifest very slowly or only when several hundred thousands of people have been vaccinated. Till a more in-depth study comes in the form of scientific papers in prestigious journals, we cannot give a definitive answer to the long-term safety of Moderna, Pfizer or other vaccines in the pipeline.

Light at the end of the tunnel or another tantalizing wait?

Probably the world will need more than one type of vaccine. The Pfizer vaccine will be suitable for some places whereas the Moderna vaccine may be a better fit for other regions. Also, if more than one vaccine is approved soon, the challenges of manufacturing enough doses and distributing them equitably across the globe (including the rich as well as the poor countries) will be less insurmountable. In this case, we may confidently say, the more the merrier!

For India, the prospects of large-scale vaccination will be much brighter if the indigenous vaccines such as Covaxin and ZyCoV-D gets approved soon, after the necessary clinical trials. Or, if global vaccines made by Indian partners such as SII (CoviShield), Dr Reddy's (Sputnik V), and Biological E (J&J vaccine) and Serum Institute of India (SII, Novavax vaccine) etc. surmounts all the hiccups and clears the regulator body's requirements for licensing and manufacturing in the near future.

Meanwhile, we must keep our fingers crossed to assess if there is really a light at the end of the tunnel or if we must be prepared for another tantalizing wait for a safe and effective vaccine. In addition, we must not let our guards down and we must still strictly observe the non-pharmaceutical interventions such as the use of face masks, physical distancing, and hand hygiene and avoidance of 3 Cs: crowded places, close-contact settings, and closed spaces (with poor ventilation).

(The views expressed are the writer's own)

First Published:Nov. 22, 2020, 3:24 p.m.

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