Segaloff HE, et al. - In view of the observed variation in influenza vaccine effectiveness (VE) by season, circulating influenza strain, age, and geographic location, researchers estimated VE against influenza hospitalization among children six months to eight years at Clalit Health Services hospitals in Israel in the 2015-16, 2016-17, and 2017-18 influenza seasons using the test-negative design. They computed the estimates for full and partial vaccination. Including 326 influenza-positive cases and 2821 influenza-negative controls (140 cases and 971 controls from 2015-16, 36 cases and 1069 controls from 2016-17, and 150 cases and 781 controls from 2017-18), they noted that fully vaccinated Israeli children were able to avoid hospitalizations with reception of influenza vaccine over three influenza seasons, but not partially vaccinated children. They identified cross-lineage protection in a season where the vaccine contained B/Victoria and the circulating strain was B/Yamagata, but not in a season with the opposite vaccine-circulating strain distribution.