Many are gut-based, but chronic respiratory symptoms, skin problems, migraines and numerous other complaints have been attributed to intolerances too.

This places us in an impossible ethical situation: if we go to work with even minor respiratory symptoms we risk infecting countless vulnerable patients.

It has been linked to increased respiratory symptoms, hospitalization rates and mortality.

There have been only small studies suggesting a possible benefit from hydroxychloroquine and chloroquine in relieving the respiratory symptoms.

Ten days later, a couple in their mid-forties who had attended the carnival were admitted to hospital with mysterious respiratory symptoms even though they had no underlying health conditions.