Use of live viral vaccines after HCT: Still a lot to learn.

Revaccination program after HCT is necessary due to the loss of lifelong immunity acquired by previous vaccination or infections. The program is complex and even in a favourable scenario, it takes more than 2 years to be completed. As the complexity of HCT increases (alternative donors, diversity of monoclonal antibodies), studies evaluating the response to vaccination in this population are welcome, especially those that evaluate live attenuated vaccines given their scarcity. Furthermore, measles, mumps, rubella and even yellow fever, and poliomyelitis outbreaks have perplexed infectious diseases clinicians and epidemiologists globally, most of them due to the decline in vaccination coverage rates in children and adults, because of the growth of antivaccine movements around the world. The study of Lin et al. adds important information about measles, mumps and rubella vaccination after HCT.