Covid-19 Vaccine Hopes: How Far Human Trials Have Progressed & Which Candidate Has Best Shot

Covid-19 Vaccine Hopes: How Far Human Trials Have Progressed & Which Candidate Has Best Shot

As the coronavirus pandemic continues to spread unabated, cumulative cases in India breached the one million-mark on Thursday. With little or no signs of the pandemic slowing down across large parts of the world, the race for developing experimental vaccines is progressing at a breakneck speed that has not seen before. In just six months since the virus came into existence, 140 vaccine candidates (vaccines under experimentation) are in the pre-clinical trial stage and 23 are in the clinical evaluation stage, according to the World Health Organization (WHO).

In normal times, vaccine development takes years as research is largely dependent on grants and funds. The widespread impact of the pandemic has spurred governments, pharmaceutical companies and global alliances to fund vaccine research more liberally, thus contributing to a speedy development in a big way. The types of vaccines also differ, ranging from ones that use an inactivated or dead virus to trigger an immune reaction to non-replicating viral vectors which involves using a different, harmless virus to deliver the pathogens into the body for generating an immune response.

Among the 23 vaccine candidates that have entered the human trial stage, delves into the progress of four experimental vaccines; two Indian and two international ones.


US-based Moderna was the first company to be off the blocks with a vaccine candidate. The company created the first doses of its mRNA-1273 (messenger RNA) vaccine in 42-days flat and sent it to their partner, the National Institute of Allergy and Infectious Diseases for testing. It was the first vaccine to enter the preclinical animal studies stage and first to examine the vaccine on humans.

According to, a US-government registry of clinical trials, Moderna’s vaccine will start the crucial Phase-III of clinical trials at the end of July. Around 30,000 participants aged 18 years and older will be enrolled for this trial that will evaluate the efficacy, safety and immunogenicity or immune response of the body after the vaccine is injected.

The randomised, stratified, observer-blind, placebo-controlled study will see one group receiving one intramuscular injection of 100 microgram and one group will be administered a placebo or dummy injection.

According to the National Institutes of Health (NIH), the national medical research agency of the United States, mRNA vaccine directs the body’s cells to express or create a virus protein to spur an immune response. The Phase-I studies, meant to test the vaccine’s safety, began from March 16. The results of this phase, involving 45 healthy people aged 18-55 years, were published recently in the New England Journal of Medicine (NEJM).

The results were encouraging and the vaccine induced anti-SARS-CoV-2 immune responses in all participants, and no trial limiting safety concerns were identified, the paper published in NEJM stated. Three-doses were administered to the trial participants and a strong immune response was seen. However, there were side-effects seen after the third dose.

The most commonly reported side-effects or adverse events were fatigue, chills, headache, myalgia. Some also experienced pain at the injection site and these effects were mild or moderate in severity, the paper stated.

Oxford University – AstraZeneca vaccine

(Indian partner – Serum Institute of India, Pune)

If Moderna was the first to be off the blocks with the experimental vaccine, then the vaccine developed at Oxford University in collaboration with AstraZeneca has been touted as one which is the most advanced stage of clinical trials. The vaccine has been developed by a team at The Jenner Institute, University of Oxford and Phase-I trials had begun in England to test safety and efficacy in late April. On April 30, the University of Oxford and AstraZeneca announced an agreement for the global development and distribution of the university’s potential vaccine.

“Under the agreement, AstraZeneca would be responsible for the development and worldwide manufacturing and distribution of the vaccine”, the company’s press release on the agreement read.

The Oxford vaccine is called ChAdOx1 nCoV-19 and it is made from a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and it has been genetically changed so that it is impossible for it to replicate in humans, the University of Oxford said.

The vaccine type is known as a viral vector type since it uses a harmless virus as a carrier to deliver the genetic material of a pathogen into cells to create an immune response. Even though the Oxford team has not released any data on the trials so

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