The Latitude Hypothesis may explain seasonal variation in occurrence of flu and influenza-like illness, including SARS-CoV-2. We focus on one variable, vitamin D adequacy in the general population, and consider statistics of two sub-populations to propose a possible treatment to improve outcomes. Communicated by Ramaswamy H. Sarma. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group.