COVID-19: An Outline of the Various Candidate Vaccines

COVID 19 Vaccines

The COVID-19 pandemic has crippled the world economies with as many as 3,747,504 confirmed cases and 258, 974 deaths already reported. The outbreak has engulfed 212 countries and territories globally along with 2 international conveyances.

India recorded its sharpest single-day spike in coronavirus cases and deaths with the infections climbing to a staggering 46,711 and deaths crossing the 1,500-mark on May 5, 2020.

WHO’s ‘Solidarity’ Initiative

As countries around the world are trying to stamp out COVID-19 outbreak, the World Health Organization (WHO), in association with its partners, has pulled efforts through its unique ‘Solidarity’ initiative. Solidarity is an international clinical trial campaign to facilitate the search and identification of an effective COVID-19 treatment.

In the same light, WHO is accelerating its assistance for the research, development, evaluation and availability of a safe and effective COVID-19 vaccine. The organization has ramped up collaborations and is convening vital communications within the research community and beyond.

WHO endeavors to run clinical trials of several vaccines as nothing is known about their efficacy and safety in advance. The motto is that the more the number of candidate vaccines tested, the higher are the chances of one turning out to be successful. WHO’s target remains to test a vaccine in its early stage of development. Another big challenge that is encountered is how to scale up the production to meet the demands of the whole world. In this direction, WHO continuously aligns R&D, fast-track regulatory approvals and productions to ensure that the global population gets a vaccine as soon as possible.

So far, more than 120 vaccines have been presented to WHO by different countries around the world. The organization is closely examining and tracking details, including the type and progress of each vaccine. At the moment, 70 vaccines are in the pre-clinical evaluation phase and 6 vaccines in the middle of clinical evaluation.

Simultaneously, WHO has pulled off ‘Global Target Product Profile’ (TPPs) as a set of guidelines for vaccine developers that lay out the minimum and desirable traits of what are characterized as safe and effective vaccines.

    TPPs focus on two different kinds of vaccines:

  • Vaccines for protection of individuals at higher risk, such as healthcare workers
  • Vaccines with rapid onset of immunity to be used in response to the widespread outbreak

Further, WHO has prepared ‘A Coordinated Global Research Roadmap: 2019 Novel Coronavirus’ that underlines goals of global R&D, proposed strategic approaches, critical actions, immediate steps to control the pandemic, selected knowledge gaps, cross-cutting research priorities, innovation actions and many other aspects related to the scientific research and contributions to control the outbreak.

Notably, WHO has also defined a ‘Draft Landscape of COVID-19 Candidate Vaccines’ that enlists the various potential vaccines for coronavirus along with their current status of clinical evaluation or regulatory norms. While most of the candidate vaccines are in the preclinical stage, a few of those running in clinical trials are discussed below:

ChAdOx1: Scientists at the Jenner Institute, the University of Oxford, have developed this vaccine which is a reinvention of a previous vaccine against an earlier coronavirus strain. Previous trials involving similar inoculations were found to be harmless for humans.

The National Institutes of Health, Rocky Mountain Laboratories, Montana, has inoculated six rhesus macaque monkeys with single doses of the vaccine and found the monkeys recovered completely after exposure to heavy amounts of the Sars-COV-2 virus that is causing the pandemic. Now, the Oxford group awaits mass human trials, following which production of 1 million doses is anticipated to complete by September. The Oxford panel has already started partnering with global institutions, including Serum Institute of India for the manufacturing of the vaccine. In a big relief, the vaccines are being produced well ahead of time in anticipation of its successful trials in the UK, working closely with various groups and philanthropists to ensure worldwide supply, including in less-privileged countries. Prof. Sarah Gilbert is the Lead Researcher along with Prof. Andrew Pollard, Prof. Teresa Lambe, Dr. Sandy Douglas, Dr. Catherine Green and Prof. Adrian Hill.

LNP-Encapsulated mRNA: Moderna tied up with investigators at the National Institute of Allergy and Infectious Diseases (NIAID) Vaccine Research Center (VRC) to develop mRNA, a potential nCoV-19 vaccine. mRNA or messenger RNA carries out the essential function of transferring the instructions stored in DNA to create the proteins required in each living cell in the human body. In other words, the single-stranded molecule, mRNA, transports genetic code from DNA in the nucleus of a cell to ribosomes which are responsible for producing proteins. An mRNA drug would instruct the cells in our system to produce proteins that could work as a remedy or prevention against a disease. Previously, Moderna joined hands with the NIH on a MERS-CoV vaccine which is a different kind of coronavirus than Sars-COV-2 causing the current pandemic.

Adenovirus Type 5 Vector: Developed by CanSino Biologics Inc. and Beijing Institute of Biotechnology jointly, the vaccine uses a non-replicating viral vector as its platform to develop a 'Adenovirus type 5' candidate vaccine. This is similar to non-corona candidates, such as an Ebola vaccine. Adenoviruses are common viruses that can introduce potential antigens to trigger the production of disease-fighting antibodies. It was CanSino Biologics Inc., in collaboration with the Chinese Academy of Military Medical Science's Bioengineering Institute, that had developed an Ebola vaccine in 2017.