Thus far, only two studies have investigated seasonal variations of primary immune thrombocytopenia (ITP) incidence in children. Results have shown a temporally correlated increase in ITP incidence during the spring and early summer [1,2]. We recently assembled a cohort of incident ITP patients within the national French insurance claim database between 2009 and 2011 (n=3771) [3]. This population-based study demonstrated a peak of ITP incidence in January and a nadir in August among both children (aged <15years) and adults [3].
