Rapid antigen tests to screen vast populations are becoming the latest weapon in Europe’s fight against the coronavirus.
But not so fast, say public health experts. More and more are concerned that people are being used as lab subjects in a vastly expensive experiment.
Slovakia recently pulled off a feat in mass screening its entire adult population, allowing those who reported negative results to win back basic freedoms like going into shops. Austria is also scheduled to test the majority of its population when its current restrictions lift in early December. The intention is to allow small gatherings for Christmas and prevent a New Year’s lockdown.
The U.K., meanwhile, is trialing mass testing in the city of Liverpool, with ambitions of carrying out 10 million tests a day, dubbed “Operation Moonshot.” It’s also testing contacts of infected people, allowing them to avoid quarantine if they test negative with rapid tests daily for a week. And some EU airports are now routinely mass screening travelers ahead of boarding.
At first glance, early results from Slovakia and the U.K. look promising as a way to lower case numbers. Slovakia this week announced three more rounds of screening by Christmas, involving 8 million antigen tests. And cases in Liverpool have fallen “quite remarkably” following mass testing rollout, according to U.K. Health Secretary Matt Hancock on Monday.
A key advantage to antigen tests is that they’re seen as cheaper, faster alternative to PCR tests. “They will be detecting disease in large numbers of people who have never previously even received a test,” said John Bell, regius professor of medicine at the University of Oxford.
But public health experts warn the tests aren’t reliable enough to detect people without symptoms — and that researchers require more rigorous studies to understand how best to use them. They also caution that pinning hopes of a safe Christmas on these tests could do more harm than good — and is more a political PR stunt than good science.
“Rushing out tests to get a good headline without having first evaluated them, with the risk that it could actually cause more infectious people to be falsely told they are negative, seems irresponsible,” said Angela Raffle, honorary senior lecturer at Bristol Medical School Population Health Sciences, University of Bristol.
How sure is sure?
Instinctively, mass testing seems like a logical approach to identify cases and contain them. Add to that the political seal of approval, as health ministers, prime ministers and even European Commission President Ursula von der Leyen have praised these tests and sought to buy them up in bulk.
At issue, however, is the limited data, and what these tests are promised to unlock, be it Christmas with relatives or a safe flight.
First is the accuracy of the tests themselves. Slovakia’s Prime Minister Igor Matovič said that one of the two rapid tests used (RapiGEN and SD Biosensor) is able to detect over 96 percent of positive cases, compared with PCR tests.
However, another study suggested results are “much lower than those reported,” according to an article in The Lancet.
The U.K. government has bought Innova rapid antigen tests. Clinical assessment from Public Health England and the University of Oxford showed it detects over three-quarters of positive cases among those who have the disease.
However, Jon Deeks, professor of biostatistics at the University of Birmingham, has dug into the data and says the true figure could be far lower: In the two studies that most closely replicate real world use, between 57 percent and 73 percent of cases were detected.
In addition, a U.S. study showed these tests don’t detect cases in the early stages of illness. “So this test isn’t good enough to pick up people in the first part when they will be infectious,” Deeks said during a recent press webinar.
Jenny Harris, U.K. deputy chief medical officer, on Tuesday acknowledged the varying accuracy based on different settings, but assured lawmakers during a parliamentary committee: “They will work very well over the infectious period.”
These data, however, seem a far cry from Hancock’s comments in April, when he defended the government’s relatively slow response in delivering PCR swab tests. “An unreliable test is worse than no test,” he said at the time.
Today, as PCR tests are hailed as the gold standard, Hancock and his team are keen to roll out hundreds of thousands of less accurate rapid antigen tests to far greater populations.
Money and ethics
But it’s not just the tests themselves that affect accuracy; it’s how they are used and who carries them out.
Deeks pointed out that a study of the Innova rapid test delivered 16 percentage points better accuracy when carried out by experienced nurses, rather than by people trained only to do swab tests, the latter most closely reflecting the practice in Liverpool.
One aim of mass screening healthy populations is to contain the infection among those who have the disease without knowing it. But it’s not known what contribution asymptomatic people make to transmission, noted Allyson Pollock, clinical professor of public health at the University of Newcastle.
“Current research suggests they play a far less significant role in transmission than people with symptoms,” she said. “So the question is why is the government undertaking mass testing or screening of healthy people when the research studies have not been carried out?”
“It’s bad medicine and unethical as well as a huge waste of resources to experiment on people,” she added.
“These issues need to be worked out, which is why pilots are being run,” said Harris, during the parliamentary inquiry.
For now, countries are taking different approaches to check the tests’ accuracy.
While patients who test positive with a rapid test in the Liverpool trial must contact their doctor to arrange a corroborating PCR test, France has opted for the opposite: To re-test with PCR those who test negative with the rapid test.
France also changed the law earlier this month to allow antigen tests to be used to boost existing testing capacity among symptomatic people as well as expand its screening programs. However, the government has been criticized for complicating the rules around their use.
For their part, many airlines have welcomed the arrival of rapid tests for the convenience of getting results in minutes — perfect, in theory, for in-airport checks. Some of Europe’s busiest airports, including in Milan, Rome, Frankfurt, London and Paris, are planning, trialing or using these tests.
Belgium’s aviation sector has been lobbying for this approach as well, but DG MOVE Director General Henrik Hololei recently warned against it.
“The worst thing to do is rely on tests which don’t deliver the results needed in terms of reliability,” he said at a recent event. “It’s very important to focus on the best testing results, not the testing volumes.”
To Raffle, the U.K. government seems to be shifting away from the science, “a change in our approach.”
“We’ve fought so hard for good, transparent evaluation,” she said. “We seem to be cutting corners in an unethical and unscientific way. And it doesn’t serve the public interest.”
The desire for normal
The number of daily infections has stabilized in Slovakia over the past week at around 2,000, although there’s no definitive evidence that mass testing is a factor. People have been able to lead relatively normal lives thanks to the program, which was carried out for the second time this past weekend, though on a smaller scale.
Matovič continues to threaten lockdown — which is strongly opposed by most Slovaks — as an alternative to screening.
However, after a lower turnout with the voluntary tests over the weekend, he said the next three rounds “can’t be voluntary,” arguing it otherwise would be a “waste of money.”
Another ongoing debate is cost effectiveness.
In the U.K., the tab might rise to £100 billion to deliver 10 million rapid tests a day. It’s not money well spent, according to Pollock.
“The government seems to be making this up as it goes along to get rid of the billions of pounds of tests that it bought,” she said. “This is a massive experiment using the public as guinea pigs without thinking it through.”
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