NEW DELHI : Vaccine design is still an empirical, trial and error process and a preventive against COVID-19 could be at least a year away, say scientists as information on developments in therapeutics to combat the infection flows in a steady trickle from across the world.While quelling the buzz of a quick breakthrough, the scientists also hold out hope that the process might be cut short by a few months if testing approvals and scale-ups in manufacturing happen simultaneously.According to the World Health Organisation, 10 candidate vaccines for COVID-19 are in the clinical evaluation and 126 are in the preclinical stage.