To assess the adherence to the second dose of ChAdOx1 nCov-19 vaccine (Covishield) among the registered beneficiaries during Phase 1 of vaccination, to determine its efficacy as to the incidence of infection post vaccination and to evaluate the severity of the infection and its association with the onset time of infection. A prospective single centered observational design was conducted 5 months among the healthcare providers and front line workers registered for vaccination. All the partially vaccinated participants were provided counseling for their second dose, and follow up was done on the due date and 60 days post vaccination to assess their compliance towards next shot and occurrence of COVID 19 infection correspondingly. Out of total 694 participants enrolled in the study, majority of participants (n= 425, 61.2 %) fall into 18-45 category followed by 45-59 category (n= 217, 31.2 %).Female participants were predominant (n= 404, 58.2%) over males (n= 290, 41.8%). Participants with normal exposure (n =338, 48%) were more than close contacts to susceptible individuals (n=325, 46.8%).Greater number of participants (n= 686, 98.8%) adhered to second dose on time according to the guidelines and as per instructed compared to those showed non adherence (n=8, 1.2%).11 (1.6 %) stated confirmation for COVID 19 infection while majority of participants’ (n= 683, 98.4%) reported neither infection nor symptoms on follow up. Assessment of severity of symptoms among the infected participants revealed that considerable portion had moderate symptoms (n=6, 1.5%) of infection while 4 (0.6%) had mild symptoms. Implementation of COVID 19 vaccination opens a new window for the development of herd community. A coordinated and harmonized mass vaccination program elevates the development of a complete herd community.