Mass testing in Slovakia helped cut coronavirus rates by 61% in one week, study suggests

Watch: Slovakia tests nearly half its population for COVID-19 in one day

Mass testing substantially cut coronavirus cases in Slovakia, research suggests.

In the UK, experts have previously questioned officials’ plans to regularly swab large groups of people for the infection.

Dubbed “Operation Moonshot”, the programme aims to identify asymptomatic cases. A lack of symptoms may mean patients do not know to isolate and could unwittingly infect others.

After being piloted in Liverpool, a group of experts warned it was unclear whether mass testing reduced deaths, with the approach potentially making matters worse if the swabs turned out to be inaccurate.

Scientists from the London School of Hygiene & Tropical Medicine (LSHTM) have since found, however, mass testing around 80% of Slovakia’s population during the country’s lockdown coincided with a 61% reduction in coronavirus infections in one week.

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This has largely been put down to household quarantines after one member of the home swabbed positive.

While mass testing is expensive and “logistically very challenging”, the scientists stressed it could “allow countries more flexibility with their restrictions”, which would be of “huge benefit to citizens”.

They added, however, the programme was effective in collaboration with social distancing, which should be viewed as a package.

The preliminary results have been published on medRxiv, “the preprint server for health sciences”, and are yet to appear in a peer-reviewed journal.

“The COVID-19 [the disease caused by the coronavirus] pandemic has changed our way of living,” said study author Dr Sebastian Funk.

“Mass testing of a country’s population will be expensive and logistically very challenging.

“However, our work shows this strategy, especially when targeted at areas with high levels of infection, could allow countries more flexibility with their restrictions to the huge benefit of their citizens.”

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Operation Moonshot aims to expand daily testing from around 650,000 a day to 10 million every 24 hours by the end of 2020.

The eventual goal is “mass testing of all homes in local areas or whole cities when prevalence rises”.

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Between 23 and 25 October, residents in Slovakia’s four most coronavirus-affected counties were swabbed for the infection as part of a pilot mass testing programme.

This was rolled out nationwide from 31 October to 1 November.

High-prevalence counties were targeted again with a subsequent mass testing regimen between 7 and 8 November.

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All residents aged 10 to 65 were invited for a swab, carried out by a healthcare professional. Out of Slovakia’s 5.4 million residents, around 80% attended.

Those who swabbed positive had to quarantine for 10 days, along with other members of their household. Failing to get tested also resulted in a 10-day quarantine.

Results suggest that within one week of mass testing, the proportion of infections picked up by a swab declined by an average of 61%.

Within two weeks, and two rounds of testing in the pilot areas, the reduction was 82%.

“Slovakia’s strategy identified more than 50,000 infections, many of which would otherwise have been missed,” said co-author Dr Stefan Flasche.

“Importantly, we found the biggest impact of mass testing is achieved by quarantining the household contacts of those who test positive.”

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The scientists acknowledge the results were due to a combination of mass testing and lockdown.

Demonstrating the effectiveness of lockdowns, scientists from Imperial College London recently found the number of coronavirus cases detected by swabs fell by nearly a third (30%) in the UK two to three weeks into the “stay at home” measure.

Nevertheless, the LSHTM team maintain their results suggest mass testing was the main driver of the reduction in Slovakia’s cases.

When asked whether the Slovakia results could apply to the UK, which has a population of more than 66 million, Dr Flasche said he is “not an expert” on the logistics of scaling-up mass testing.

He added, however: “If done in the right way, mass testing has the potential to have a very large effect.

“We need to understand where the trade off is between logistical burden and reducing infections.”

Not everyone is convinced of the benefits of mass testing, however.

Among symptomatic patients, some research implies people are at their most infectious before they feel ill.

“The window of opportunity where someone is unknowingly infectious is probably a matter of days,” Dr Angela Raffle from the University of Bristol previously said.

“For [mass screening] to work, you’d have to test everyone every few days.”

Furthermore, no coronavirus test is perfect, which could lead to missed cases and even undermined public confidence if swabs are reported as being inaccurate.

Experts have also warned about the price of mass testing.

A society-wide approach would cost “more than any other healthcare intervention contemplated”, which could “cause harm through significant diversion of resources”, according to the skeptical team of experts, who came from different universities.

In September, a leaked government report revealed plans for mass testing would cost around £100bn ($73.3bn) – three-quarters of the total annual funding for NHS England, according to The Week.

Dr Martin Pavelka – co-author of the LSHTM study and member of Slovakia’s ministry of health – argued: “Population-wide COVID-19 interventions such as lockdown result in a huge social and economic toll.

“This is because they target everyone, not just those who are actually infected and spreading the disease.

“Low-cost rapid tests that can be produced at large scale may offer the opportunity to conduct mass testing campaigns which identify most infectious individuals.”

Population screening for the coronavirus is not endorsed by World Health Organization or the government’s Scientific Advisory Group for Emergencies (Sage).

Although unclear what the best approach is, the skeptical team previously said focusing on symptomatic cases and their contacts – as well as vulnerable populations – would be the most effective way of stemming the outbreak.

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