Bhubanananda Sahu
The world is faced with a grim situation due to spread of the corona virus pandemic. As many as 213 nations are under the virus’ grip and deaths are one too many. A vaccine is what can change the present scenario for the better, and efforts in this direction are under way in various scientific institutions.
A vaccine is a substance that, when injected, will accord an individual greater resistance to fight the disease. World Health Organisation has identified 10 candidate vaccines for human clinical trial and 115 candidate vaccines for pre-clinical trial by May 27. Out of the ten, four are registered in China, one in the European Union and five in US. In the 10 candidate vaccines, four vaccines are made on the existing platform where the vaccines for Ebola, SARS, MERS etc were developed.
According to Nature journal and the Alliance for Science, Cornell University, the top five candidate vaccines are: China’s CanSino Biological adenovirus vaccine (Ad5-nCoV), Oxford University’s adenovirus vaccine (ChAdox1), Boston based Moderna’s mRNA vaccine (mRNA 1273), Chinese company SinoVac’s inactivated virus vaccine (PiCoVacc) and Inovio’s DNA vaccine (INO-4800). The Oxford team had, on May 13, reported that their adenovirus-based vaccine ChAdox1 prevented monkeys from getting pneumonia when infected with SARS-CoV-2. This adenovirus caused infection in chimpanzees but has no replication as to cause an infection in humans. This is an existing platform-made vaccine for MERS, influenza, TB, Chikungunya, Zika, MenB and Plague.
Boston-based Moderna’s RNA vaccine has some advantages but laboratory production of the protein is avoided. Moderna’s RNA vaccine was injected in humans in mid-March. In May, the management team announced that the vaccine has stimulated an immune response with produce of neutralizing antibody in eight volunteers; which was a very promising development. This RNA vaccine might make a revolution of rapid production with unimaginable speed as against traditional ones.
The inactivated pathogen vaccine that has undergone a clinical trial by Chinese company SinovaC is designed by isolating SARS-CoV-2 samples from infected hospital patients and growth of the virus in a cell line before inactivating it with chemical treatment. The name of the vaccine is PiCoVacc which stands for purified inactivated SARS-CoV-2 vaccine.
The DNA vaccine is also a new technology like RNA vaccine. Here, the circular plasmid is injected into human cell. The viral protein is expressed in cell and helps the immune system to fight against any attack by Covid-19. Inovio made the vaccine for Covid19 with name INO-4800. The related scientific fact was published on May 20 by scientists through Nature journal and here they stated that the candidate vaccine INO-4800 showed robust binding and neutralizing antibody as well as T-cell response in mice and guinea. The vaccine development is a long process. The H1N1 pandemic in 2009 started in March and WHO announced a version of a vaccine by September the same year. Experts say that the key reason for this speed in development of a vaccine was previous knowledge of production in chicken egg and on a cell-based platform that could be licensed under the rules used for a strain change. There is also evidence of an accelerated 5-year time-scale for development of the first Ebola vaccine. The following are the common timelines to develop a vaccine — chicken pox, 42 years (1953-1981) and Hepatitis B, 16 years (1965-1981).
Vaccine development for any disease means following some precise steps. The steps are identification of outbreak of the germ, research in the lab to understand the physiology and attack tactics of the germ to humans, the preclinical trials in animals, clinical trials in humans with three phases, the food and drug administration’s approval and at the end the vaccine’s commercial production. According to a report in the New England Journal of Medicine, a preclinical animal study would last one or two years, clinical trial phase 1 would take a year or two, the phase 2 would take 1 to 2 years, the phase 3 some two to three years, the FDA approval some two years, and start of manufacturing would take six months’ time. Thus, it takes six to ten years to develop an effective vaccine for people.
The writer is research scientist at University of Massachusetts Medical School, USA.