Efficacy of SARS-CoV-2 vaccines - A big challenge ?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the resulting disease, the coronavirus infectious disease 2019 (COVID-19), have spread to millions of persons worldwide resulting in pandemic.The cases of Covid 19 doesn't seem to end to soon.There are about sixty-two million six hundred nineteen thousand three hundred ninety-ninecases at present in the world with India ranking second after USA with nine million three hundred ninetythree thousand thirty-nine cases.Adoption of infection prevention and control practices such as hand hygiene, respiratory etiquettes, and maintaining social distance are the important strategies for the containment of this deadly and stubborn novel corona virus.The multiple vaccine candidates are under trials,to evaluate their clinical efficacy.The vaccination aims is to generate immunity against COVID-19 and to protect oneself against the disease and limits the spread of disease to close contact