Coronavirus and COVID-19 infections continue to wreak havoc across the world. Interestingly, the COVID-19 infections and deaths display a clear seven-day cycles. Mathematical analysis using linear mixed-effects models show that this periodicity is not due to reporting errors. We hypothesize that these COVID-19 cycles are related to natural immune cycles which also oscillate every seven days. These immune cycles are regulated by stress and mediated through the endocrine and the central nervous systems. Our routine activities and lifestyle of more stressful weekdays flanked by less stressful, relaxing weekends define the seven-day immune cycles. The synchronized low immunity levels in the population is responsible for repeated seven-day waves of pathogenic infections such as COVID-19. The new understanding of the role of immune oscillations will help in developing strategies to enhance our immunity through modified lifestyle and better, innovative prophylactic and therapeutic approaches against infectious diseases.