The COVID-19 pandemic is one of the most significant events in modern human history. It is ongoing and any means that can be used to understand its dynamics is critical for mitigating its harmful effects. Most COVID-19 studies are justifiably biologically oriented. Nonetheless, given the wealth of data that are available, COVID-19 can also be studied from a mere signal processing perspective. Recent reports in the news have discussed a putative 2-month cycle in COVID-19 cases, which prompted us to conduct a rigorous time series analysis. Our analysis indeed finds strong evidence for cyclicity, but the period is more like 4 months and a long-term modulation of its amplitude is also present. These quantitative results imply that “waves” in pandemics are controlled by an intrinsic viral cycle and knowing this can be used to predict and prepare for them.