Omicron and the logic of testing

THEN 29 DECEMBER Britain has recorded 246,215 cases of covid-19, a number more than three times the previous peak a year ago. If Britain’s level of immunity were the same as in the winter of 2020, when almost no one had been vaccinated, this number of cases would constitute a new disaster order. Several thousand people would die every day. But thanks to vaccination, they are not. The proportion of people who have died after testing positive for covid-19 is now around one-twentieth of what it was last winter.

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It is against this backdrop that the government is considering stopping providing free lateral flow tests to the public, a policy which has cost more than £6bn ($8.2bn) to date. In the face of public outrage, it has recently faltered, but there is no doubt that the supply will end soon. The timing, however, is tricky. the NHS is stretched thin. Scientists and public health experts fear that a high number of cases could leave large numbers of people with the post-viral conditions collectively known as long covid, and that ending free testing would provide a boost to the virus. Some people have grown accustomed to the license conferred by the single pink line of a test taken before reuniting with friends or colleagues.

But the properties of Omicron change the logic of the tests. It is far more transmissible than previous variants and drove its predecessors to extinction worldwide in just one month. There is no chance of eliminating it; even China, with all the authoritarianism of which it is capable, will fail. In addition to spreading through a population with much stronger immunity, Omicron also causes inherently milder disease than previous variants. This is thanks to its evolved tendency to infect the upper respiratory system rather than the lower respiratory system.

All of this means that the risk of people dying or being hospitalized because an untested person unknowingly transmits the disease is lower than it has ever been. By contrast, the risk of essential services being interrupted because people are forced to self-isolate after testing positive is higher than ever. Chris Hopson, owner of an association of NHS hospitals, said on January 8 that shortages caused by staff isolating after testing positive were causing an “equally if not more important” problem than the influx of covid-positive patients. Even though more Britons have tested themselves than ever before over the past month, the virus has spread widely.

For some people, the balance of costs and benefits now argues in favor of ending the free distribution of lateral flow tests. “The downside of having people passing on what is essentially a common cold is not very serious,” says Sir John Bell, Regius Professor of Medicine at the University of Oxford. “Spending a lot of money on a testing regime that locks down a lot of people and means the economy is not moving forward; there is a significant downside to this.

But the testing infrastructure must be kept ready to restart in the short term, warns Sir John, in case a new variant changes the cost-benefit equation again. Too little is known about viral evolution to be sure that one will not emerge that is as infectious as Omicron but causes many more serious cases.

As Britain mulls the end of its free lateral-flow testing scheme, America is just beginning to hand out its own free tests. Omicron’s logic is different there, because fewer people are fully vaccinated. Other countries will be watching Britain’s situation, to see if Sir John and the government’s calculations are correct and if ending widespread asymptomatic testing actually proves beneficial overall. As the pandemic wanes and the focus on whether or not someone is infected with covid-19 fades, public attention to daily case counts may also diminish.

Throughout the pandemic, the UK government has tended to hesitantly add protective measures and decisively remove them, a trend that has drawn criticism. Its rapid adoption of free lateral flow testing went against the grain. Ending the diet will feel like giving up a cozy blanket. That doesn’t mean it’s wrong.

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This article appeared in the Great Britain section of the print edition under the headline “Look away”

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