FILE PHOTO: An elderly man receives a coronavirus disease (COVID-19) vaccine booster coinciding with the flu vaccination campaign in Seville, Spain October 18, 2021. REUTERS/Marcelo del Pozo
FILE PHOTO: An elderly man receives a coronavirus disease (COVID-19) vaccine booster coinciding with the flu vaccination campaign in Seville, Spain October 18, 2021. REUTERS/Marcelo del Pozo