Public health officials have been warning that a COVID-19 vaccine will not be available to the public for 12 to 18 months, dampening hopes that there will be a quick end to the global pandemic nightmare. The grim truth behind this rosy forecast is that a vaccine probably won’t arrive any time soon. Clinical trials almost never succeed. We’ve never released a coronavirus vaccine for humans before. Our record for developing an entirely new vaccine is at least four years — more time than the public or the economy can tolerate social-distancing orders.\Traditionally these antigens are in a weakened or inactive form, so they cannot actually cause the illness. But our immune system is then able to recognise the antigen as an unwanted foreign invader, and forms antibodies, allowing it to “remember” the pathogen in case it tries to infect you in the future. The antibodies you have built up will then attack the pathogen before it is able to make you unwell if you are exposed to it in the future.Now mRNA vaccine is seen as the new hope for the world, now among the most advanced in human trials (Phase-2) to screen a safe and effective COVID-19 shot that will be used on the world’s healthy population. Developing immunity to SARS-CoV-2 would render the virus no worse than the seasonal flu.There are four phases in vaccine trials, the first 3 being the most crucial.