Slovakia wants to become the first country to test its entire population for SARS-CoV-2, in a bid to contain the virus. Still, experts have warned that several logistic and technical challenges could make the plan impossible to carry out, with the president himself calling it “unfeasible”.

The government hopes to test about four million people over two weekends. The testing campaign started last Saturday, with 5,000 testing sites set up around the country. Healthcare workers from Hungary and Austria were brought in to help with the campaign. Still, long queues were a common sight.

Since summer’s end, Slovakia has seen a rapid increase in the number of COVID-19 cases. The country got a lot of international attention for its response to the virus in the first wave of the pandemic. The first infections were reported in early March and between then and September only a few new infections were recorded.

Nevertheless, authorities have identified thousands of new cases each day over the past month, with the proportion of infections per number of people tested at under 16%. The government described the numbers as alarming and warned that the country’s health sector could collapse in weeks unless the spread of the virus is slowed.

The mass testing campaign seeks to help in that regard. Everyone over the age of 10 will be asked to go to a testing site and take an antigen test. Anyone who tests positive will have to remain in strict self-isolation at their home for 10 days, or they can go to a quarantine facility provided by the state.

Many shops will remain closed during the campaign, with restrictions on movement and random spot checks in place. Those who take the test will be given a certificate to present if requested. Failure to do so could result in a fine of $1800. The testing is voluntary, but anyone not participating must self-isolate in their homes for 10 days.

While the government has said mass testing is the best way to avoid the spread of the virus, it has acknowledged the limitations of the plan. So far only 70% of the 20,000 staff needed to administer the nasal swab tests have been recruited. This has led President Zuzana Caputova to call for a rethink of the strategy. Scientists have also questioned the use of antigen tests, which the World Health Organization (WHO) says aren’t good for mass testing unless used alongside PCR tests. The government purchased tests from South Korea and claimed they have a specificity of 99·68% and a sensitivity of 96·52% compared with PCR tests.

Alexandra Brazinova, an epidemiologist at Comenius University in Bratislava, told The Lancet: “There are many risks: not communicating properly to the public the aim and process of the testing could create misunderstanding, frustration, fear, and opposition. Then there are the logistics required and the risks of infection at testing sites.”

Beyond the potential difficulties involved in the campaign, experts have also raised questions over its actual benefits. For Brazinova, this won’t stop the pandemic but it could slow down the spread, at best. The government has admitted that testing isn’t a quick fix.

There aren’t many precedents for a testing campaign on this scale. In October, China tested more than 7 million people in the city of Qingdao over 3 days. They used sample pooling in which residents’ individual samples were collected and then processed in batches of ten at a time in a single nucleic acid test. Similar tests were performed in Wuhan with 9 million people.

Supporters of mass testing in other countries have welcomed Slovakia’s plans but were cautious. Julian Peto, a UK professor of epidemiology, told The Lancet: “It sounds like a great idea, and I am delighted someone has decided to try it, but this seems like a very bad way of doing it. This kind of testing can’t be implemented overnight.”