Sick time

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Science  20 Mar 2020:
Vol. 367, Issue 6484, pp. 1294-1297
DOI: 10.1126/science.367.6484.1294


As far back as Hippocrates, it has been clear that many infectious diseases peak during different seasons. With the emergence of coronavirus disease 2019 (COVID-2019), the question of what drives this seasonality of diseases and whether this will kick in now as winter ends in temperate regions of the Northern Hemisphere has become a far more pressing question. Research into the phenomenon has led to few answers, but many intriguing possibilities. Viruses like COVID-19 and influenza have lipid membranes that some evidence suggests are particularly sensitive to changes in temperature, humidity, and the related changes in osmotic pressure, evaporation, and pH. Micaela Martinez, a Columbia University researcher who is a leader in this tiny field, is examining whether the human immune system changes with the seasons, leaving us more or less susceptible to different pathogens. Martinez suspects daily circadian rhythms, which are linked to surges of the hormone melatonin at night, link to these seasonal changes, and indeed studies have found that giving vaccines at different times of day leads to different immune responses. Ultimately, a finer understanding of the phenomenon could also refine our use of vaccines and other public health interventions.

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