So how many.doses.of vaccine do.we.needGENEVA, SWITZERLAND -- Pharmaceutical company executives said Thursday that one or several COVID-19 vaccines could begin rolling out before 2021, but warned the challenges would be "daunting" as it was estimated that 15 billion doses would be needed to halt the pandemic. Well over 100 labs around the world are scrambling to come up with a vaccine against the novel coronavirus, including 10 that have made it to the clinical trial stage. Advertisement