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.