Rediscovery of Caffeine: An Excellent Drug for Improving Patient Outcomes while Fighting WARS

The COVID-19 (here specifically called Worldwide Acute Respiratory Syndrome, WARS) pandemic is surging worldwide. Unfortunately, no specific drug meets the urgent need to fight this pandemic, leading to thousands of deaths. The theory of host-directed therapies (HDTs) is viewed as the ideal means to rephrase the treatment of infectious diseases. However, related drugs based on this theory have not been identified. Previously, we realized that caffeine is the ligand of type 2 taste receptors (TAS2Rs), which play a critical role in host defense. Here, we gathered data on caffeine acting as an immunomodulator. Unexpectedly, we found that caffeine can fight WARS by acting on multiple organs, which may prevent the virus from entering the cell, stimulate the phagocytosis of macrophages, enhance breathing, and inhibit the cytokine storm. Thus, the immunoprotective effects of caffeine can improve the therapeutic outcomes in patients infected with coronavirus. Collectively, we report that caffeine, an FDA-approved, highly safe, inexpensive, and widely available drug, could be an excellent HDT for battling WARS.