GENEVA: Moderna aims to roll out a combined COVID-flu-RSV booster vaccine in late 2023, the US pharmaceutical firm said Monday, hoping a joint jab would encourage people to get an annual shot. The single vaccine for COVID-19, influenza and respiratory syncytial virus – a common virus that causes the cold, but can be more serious for infants and elderly people – could appear on the market before 2024. "Best-case scenario will be the fall of '23," Moderna chief executive Stephane Bancel told a virtual World Economic Forum roundtable session. "I don't think it would happen in every country, but we believe it's possible to happen in some countries next year. "Our goal is to be able to have a single annual booster so that we don't have compliance issues where people don't want to get two to three shots a winter, but to get one dose." Bancel said the RSV program was in Phase III trials — the final stage of human testing — while the flu program should be entering Phase III in the second quarter of this year.