Loneliness has been a major concern for philosophers, poets and psychologists for centuries. In the past several decades, it has concerned clinicians and public health practitioners as well. The research on loneliness is urgent for several reasons. First, loneliness has been and still is extremely ubiquitous, potentially affecting people across multiple demographics and geographical areas. Second, it is philosophically intriguing, and its analysis delves into different branches of philosophy including phenomenology, existentialism, philosophy of mind, etc. Third, empirical research has shown (...) that loneliness is a significant health risk factor. Loneliness may thus be defined as a (negative) social determinant of health.Having that said, COVID-19 has demonstrated how little we as members of humanity have been prepared to face the loneliness resulting from the global response to the virus. As people worldwide are literally dying from loneliness, we still do not know what makes one feel lonely while making another feel being in solitude, or how is it that one feels lonely in the heart of London.In this essay, I first review loneliness in general and specifically in the context of COVID-19. I then argue that loneliness should be understood as a social determinant of health. Lastly, I argue that individuals have a right not to be lonely. Such right stems in turn from the right to healthcare or even a right to health. (shrink)