Chair's letter.

Dear IR community, It is happening again. Conferences that were planning to host in-person events in the first half of 2022 are switching to fully virtual events. WSDM 2022 is the latest to do so, following CHIIR 2022 which made the switch in December. While this is disappointing for all of us that were hoping to travel again, and especially heartbreaking for the conference organizers, it is clearly the right thing to do given lockdowns and travel restrictions being reinstated in countries around the world. We continue to plan for a hybrid SIGIR 2022 with an in-person event in Madrid, taking into account the possibility of COVID-related restrictions that may reduce its size---or force us to cancel altogether. [ABSTRACT FROM AUTHOR]