Coronavirus vaccine frontrunners: Vaccine candidates that are most promising

None of us has ever witnessed a health crisis like this in our lifetime. People are increasingly getting infected by the coronavirus aka COVID-19 and many succumbing to it. Health researchers and scientists all across the world are fast tracking their work on producing an effective vaccine to combat this epidemic. As expected, there is widespread interest in the vaccines right now, in the absence of a proven cure. For the unversed, there are 150 vaccine candidates that are in the works right now, according to the World Health Organisation. But there are four that are closest to the finish line. Let’s take a look at them

The vaccine was in news recently as it entered its third phase trial after showing a safe and positive immune response in the body. Developed at the University of Oxford, the vaccine has been officially named AZD1222 and its formulation is supported by AstraZeneca PLC, which is a British-Swedish pharma company. Furthermore, the latter had joined hands with Serum Institute of India (SII), which is the largest manufacturer of vaccines - in terms of doses produced as well as sold. The Phase 3 trial has started in Brazil where larger scale trials will be carried out.

Moderna has been in the news ever since the coronavirus vaccines have been discussed. Dubbed mRNA-1273, it is aimed at delivering packets of virus’s genetic code in the form of mRNA to human cells, where they make the cells produce viral protein - triggering a response from the immune system. This response will get alive if the target virus tries to attack the body. The vaccine candidate had shown promising results in the primary safety trials, as per federal guidelines. However, a big setback was faced when they realised some side effects of the vaccine candidate in the human trial phase. The researcher had said that the antibody levels produced with the vaccine were encouraging. They are working aggressively on releasing a vaccine that’s most effective.

German-based BioNTech and pharma giant Pfizer are working on an mRNA-based vaccine dubbed BNT162b1. Somewhat similar to the Moderna vaccine, this vaccine candidate makes use of a fatty nanoparticle cover to pass on the message to the cells to produce proteins. While the researchers are said to be making "good progress", the final vaccine cannot be expected before early 2021, as per a WHO health expert.

It remains unknown if the positive immune responses received from the vaccine will actually help in combating the virus, it will only be seen when it is put to the ultimate test - when it is rolled out.

Lancet journal published the phase 2 trial results of the Chinese Ad5-vectored COVID-19 vaccine, which is being worked upon by biotech firm CanSino Biologics and the Chinese military.

Similar to the Oxford-AstraZeneca vaccine, CanSino makes use of a viral vector-based vaccine, which is based on a weakened adenovirus. Interestingly, the adenovirus used is not the one that is present in chimpanzees but humans. This could be an issue as in the past exposure to human adenovirus has thrown off immune responses. The researchers had shared in their initial reports that people who were already exposed to adenovirus did not show robust immune responses in comparison to those who had not been exposed. In their phase 2 trial, almost 96 per cent people were able to build antibodies against SARS-CoV-2. Despite several concerns over the use of human adenovirus, they are planning to enter the phase 3 trial.