The MERS coronavirus—MERS stands for “Middle East Respiratory Syndrome”—causes severe respiratory diseases with a high mortality rate. To date, there is neither a vaccine nor a specific treatment. The safety, immunogenicity and optimal dosing regimen of the MVA-MERS-S vaccine candidate developed at the DZIF have now been investigated in a phase Ib study in healthy individuals who were previously infected with the related coronavirus SARS-CoV-2. The study, led by Prof Marylyn Addo at the University Medical Center Hamburg-Eppendorf, has shown that the vaccine is safe and effective.