The New Paper Seniors not getting jab out of fear of side effects: Study A medical worker prepares to dilute a vial of Pfizer-BioNTech vaccine at a coronavirus disease (COVID-19) vaccination center in Singapore March 8, 2021.PHOTO: REUTERS 0 Engagements Concerns over the safety and efficacy of the vaccines is the main reason seniors are reluctant to go for Covid-19 jabs. This was one of the lessons drawn from a study conducted by Singapore Management University's Centre for Research on Successful Ageing. The study used data collected from the Singapore Life Panel, a population representative monthly survey of Singaporeans aged between 56 and 75.