Voters casting ballots in the referendum will decide whether Switzerland should impose strict COVID restrictions.
Swiss voters are having their say on legislation to impose the use of a COVID-19 certificate that lets only people who have been vaccinated, recovered, or tested negative attend public events and gatherings.
The referendum on Sunday offers a relatively rare bellwether of public opinion specifically on the issue of government policy to fight the coronavirus in Europe, currently the global epicentre of the pandemic.
The vote on the countryâ€™s COVID-19 law, which also has unlocked billions of Swiss francs in aid for workers and businesses hit by the pandemic, comes as Switzerland â€“ like many other nations in Europe â€“ faces a steep rise in coronavirus cases.
The Swiss federal government, unlike others, has not responded with new restrictions. Analysts say it does not want to stir up more opposition to its anti-COVID-19 policies before they face Sundayâ€™s test at the ballot box.
If the Swiss give a thumbs-up, however, the government may well ratchet up its anti-COVID efforts.
Polls suggest a solid majority of Swiss will approve the measure, which is already in effect and the rejection of which would end the restrictions â€“ as well as the payouts. But in recent weeks, opponents have raised heaps of cash for their campaign and drawn support from abroad.
On Tuesday, Swiss health authorities warned of a rising â€œfifth waveâ€ in the rich Alpine country, where vaccination rates are roughly in line with those in hard-hit neighbours Austria and Germany at about two-thirds of the population. Infection rates have soared in recent weeks.
The seven-day average case count in Switzerland shot up to more than 5,200 per day from mid-October to mid-November, a more than five-fold increase â€“ with an upward curve like those in Germany and Austria.
The spike in cases comes as dozens of countries reimposed a ban on travellers from several southern African countries because of a new coronavirus strain.
The Omicron variant is a potentially more contagious variant of COVID-19. It was first detected in South Africa and has been dubbed a â€œvariant of concernâ€ by the World Health Organization.
Germany, Italy, and the United Kingdom have become the latest countries in Europe to detect cases of the Omicron variant.