COVID-19 Vaccine Development

The worldwide magnitude of the COVID-19 pandemic is ineffable; it is unsurprisingly compared to the Spanish flu pandemic, which ravaged the world during the First World War (adding fuel to the fire!). One of the pandemic's various positive impacts has been the unprecedented research collaboration and data sharing across the world. Such singular efforts made it possible to cut down the usual time to achieve an approved vaccine from 10⁺ years to less than a year.

To put things into perspective, it took 60 years from the time of the first polio outbreak to developing its vaccine; in the case of Ebola, it took 15 years. Vaccine candidates for SARS-CoV-1 and MERS did not receive the necessary impetus to advance into fruition. However, with SARS-CoV-2, the situation is very different. Global initiatives such as ACTIV (Accelerating COVID-19 Therapeutic Interventions and Vaccines), a public-private partnership comprising of bigwigs like CDC, FDA, EMA (European Medicines Agency), and numerous leading biopharmaceutical enterprises. Another project on a similar scale is Operation Warp Speed, which has invited comparison to the infamous Manhattan Project.

What is an "ideal" COVID-19 vaccine? There are three criteria from the immunological perspective: 1) It induces a robust humoral immune response that produces long-lasting neutralizing antibodies against SARS-CoV-2 antigens, 2) It generates a strong cell-mediated immunity that includes the production of memory T cells, 3) It should be free of any serious local or systemic adverse effects. Considering the logistics of vaccinating the entire world, there are three more criteria: 1) It should be easy to administer, preferably in one or two doses, 2) It should be easy to produce on a large-scale, 3) Its storage should be uncomplicated, ideally possible at room temperature.

 Source: Front. Pharmacol., 19 June 2020 | https://doi.org/10.3389/fphar.2020.00937

Let us discuss the vaccines that are currently in development. We all have heard about a few of them in the news and social media, namely, Pfizer, Moderna, Covaxin, Astra Zeneca, and so on. There are, impressively, 125⁺ SARS-CoV-2 vaccines in development globally. Broadly, there are six platforms currently being utilized for vaccine development –

1.   DNA

2.   mRNA (examples – Moderna, Pfizer)

3.   Protein (Subunit vaccines)

4.   Viral vector – replicating/non-replicating (examples - Oxford/Astra Zeneca, Johnson & Johnson)

5.   Live attenuated virus

6.   Inactivated virus

Almost all of the above models have targeted the spike glycoprotein, which is present on the surface of SARS-CoV-2, to interfere with the viral entry into a cell.

This article is an oversimplified summary of the vaccine development process. I haven't covered the vaccine platforms, molecular targets, and vaccine candidates in detail. With the advent of vaccine administration, whether it's Pfizer's or any other, there will be a massive surge in vaccine-related information. There will be challenges at every step, from distribution to underdeveloped areas of the world to alleviate the concerns of the skeptical anti-vaxxers. Let us hope that these vaccines start the end of the pandemic.

-Vinayak