Over a million Slovaks took a coronavirus swab on Saturday as the country launched a huge logistical operation to test most of its population over the weekend to reverse a rise in the pandemic.
Authorities say the ambitious plan to test most citizens aged over 10 among Slovakia's 5.5 million people is the first of its kind in a country of its size.
It is being watched by other nations looking for ways to slow the virus spread and avoid overwhelming their health systems.
More than 40,000 medics and support teams of soldiers, police, administrative workers and volunteers staffed around 5,000 sites to administer the antigen swab tests.
As of noon (1100 GMT), 828,518 people had been tested and 7,947 were positive, Defence Minister Jaroslav Nad told a news conference.
"We have clearly got to over 1 million (as of 1500 GMT) - people's interest continues," Nad said, adding that over 3 million people may be tested over the course of the weekend.
Prime Minister Igor Matovic has said he hoped the plan would identify and quarantine enough infected people to avert a strict lockdown for everyone.
The testing was free and voluntary, but the government will impose lockdowns on people who do not participate, including a ban on going to work.
Martin Janosik, a 44-year-old entrepreneur, said he had taken part so his son would be allowed to attend school.
"I did not have much of a choice, but I did not think much about it," he told Reuters at a testing centre in Trencin, a city north of the capital Bratislava.
"It is also good for me and for my company, if I am healthy I can be there and take people around."
Slovak media reported up to four-hour queues but waiting times were getting shorter in the afternoon.
Some of the sites at schools, sports grounds, theatres, car parks and companies opened late on Saturday amid lack of staff or material, but Nad said 99% of sites were operational by early afternoon.
The antigen test gives results in just 15-30 minutes but is less accurate than the molecular PCR method.
Opponents of the scheme have pointed to a Czech study that found antigen tests identified only around 70% of infections detected by PCR tests, but the government has insisted that even at that level of accuracy the exercise is worth it.
Critics also question whether requiring people to show a negative test in order to move around freely complies with data protection rules.
A second round of testing is planned for a week's time.
Slovakia reported 2,573 Covid-19 cases on Saturday through PCR testing, bringing the total to 57,664, with 219 deaths.