For March, passengers numbers fell 63.2% from a year earlier, as only 890,134 people flew via Zurich. The airport handled only 25,491 tonnes of freight, a 39.6% drop from March 2019.
The nation's biggest airport did remain open, accommodating select international connections including Frankfurt, London, Helsinki and Amsterdam.
It also handled the Swiss foreign ministry's activities in repatriating Swiss nationals stranded in other countries.
(Reporting by John Miller; Editing by Jan Harvey)