Passengers on trains, trams, buses, mountain railways and ferries across Switzerland had to don facemasks on Monday under a government order to help fight the novel coronavirus.
The government phased out most restrictive measures last month as cases waned.
But numbers picked up again as people come into closer contact, prompting the government to order passengers to wear masks on public transport.
Compliance with the new rule appeared high.
Switzerland has reported more than 32,200 infections and 1,686 related deaths as of Sunday. The first case was reported in late February.
