Amid travel restrictions, quarantines, closures, physical distancing, masking, enhanced hand washing, and disinfection, the 2020-2021 flu season was all but canceled.Still, the influenza B/Yamagata lineage remains missing, according to a study published this week in the journal Eurosurveillance.Vanished virusIn an article published this week in the journal Eurosurveillance, researchers in the Netherlands sifted through the latest global influenza surveillance data up to August 31, 2022, looking for the missing strain.They note that GISAID, a global database of influenza virus genetic sequences that typically gets thousands of flu sequences each year, has not received a single B/Yamagata sequence with specimen collection data after March 2020."From a laboratory perspective, we think it would be advisable to increase the capability and capacity to determine the lineage of all detected influenza B viruses around the world as this is critical to determine the absence of B/Yamagata lineage viruses," they conclude."