There is no scientific evidence available which suggests that coffee prevents or decreases the impact of the coronavirus.
Methylxanthines are a unique class of drugs that are derived from the purine base xanthine which is produced naturally by both plants and animals. The methylxanthines, theophylline, and dyphylline are used in the treatment of airways obstruction caused by conditions such as asthma, chronic bronchitis, or emphysema.
The Centre for Disease Control and Prevention (CDC) reports that there are no drugs or other therapeutics presently approved by the U.S. Food and Drug Administration (FDA) to cure or prevent COVID-19.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19 including symptoms, prevention, and available treatment, please refer to the World Health Organisation or your national healthcare authority.