Why a lateral flow is the ultimate stocking-filler

Every home should have one. A small pile of, mostly, blue and white boxes the size of a slim trade paperback bookmarked NHS Test and Trace COVID-19 Self-Test (Rapid Antigen Test). These test kits have become household items this year, although it is so irritating that they didn’t get the name right on the box. It took me months to be sure they were indeed Lateral Flow Tests (LFTs).

We’ve had little option but to become dab hands with the nose and throat swabs, the sachets of buffer fluid, the extraction tube and its holder, and the test strip. A negative test is either now politely requested or mandatory before being allowed into most places of entertainment, whether private or public. 

Year two of the pandemic has been different because it has been the year when science fought back. Vaccines have been universally available in the UK. Doctors have at last worked out which therapies and drugs work for with severe covid. And testing has become the key to treatment for those who test positive and freedom of movement for the negatives. 

Inevitably there has been an irrational reaction against some of the advances in the battle against the disease. Anti-vaxxers are deluded and unpleasant campaigners against the health of others and themselves. 

A friend reports encountering a young woman proudly smoking indoors at the party of a mega-rich Conservative donor. “Yes, and I’m not vaccinated either!” she boomed without prompting as they passed by. 

In spite of new orders from the government, the passive-aggressive stand-off between mask wearers and the bare-faced in public spaces continues. There is widespread fury at the high cost of the compulsory PCR tests for travellers abroad. 

But the experts say self-administered testing is the first line of defence and, in the face of a killer disease, experts are more welcome than Michael Gove thought they were during the Brexit referendum. He is now the Cabinet’s high priest of caution, and the rest of us have taken to the humble LFT without complaint – without really caring how reliable it is or indeed how much it is costing the taxpayer. 

Perhaps that is because the tests are now largely free here. They haven’t always been. Last Christmas, there was a clamour at my home to acquire some tests even though they weren’t then widely available. I duly went online and found some on the market from Roche. 

The cost, £200 each, was a bit steep but a small price to pay for domestic harmony, so I duly pressed “Buy Now”. When they arrived, instead of two tests I had bought two boxes of 25 tests each.

It didn’t matter to me much since I got pinged shortly afterwards and spent the festive season in “self-isolation” – which I still maintain is a tautology as irritating as “Feral Beasts” or “TUC Congress”. 

At least we were popular. 

The Gift of A Test Kit allowed friends and family to reassure themselves. We still have a few of these expensive original test strips left, but because they aren’t stamped with the NHS codes, they can’t be loaded up to www.gov.uk/report-covid19-result. 

When this pandemic is over, we are likely to have a stack of left-over test strips anyway, since a sachet frequently doesn’t contain enough extraction fluid to work, and we have to cannibalise juice from other sets. 

We, collectively, were not so blasé when the NHS started distributing the test kits for the first time earlier this summer. We followed the 20-page guide with minutely washing hands, wiping down surfaces and twisting the swab in our noses ten or twenty times as instructed. We set stopwatches for the requisite 15 or 30 minutes to allow the test to develop. 

Even allowing for officialdom’s assumption that the public is stupid, the deep probing of cavities has always struck me as overdone.

The very first test I had back in May 2020 was conducted under clinical conditions. The doctor and nursing assistant administering it barely touched my nose and tonsils with the elongated Q-tip. As for the long anxious wait, while the minutes tick down the C-control line shows as soon as the liquid has made its way up the blotting paper and, though luckily I have not seen this yet in person, I’m told by one who has tested positive that the T-test line appeared just as quickly. 

As I’ve noted in this diary before, there has always been an element of Covid Theatre, reassuring but hollow ritual, about the precautions we are taking. 

There is no need for spectacle with LFTs; on balance, they have worked. Lateral flows have arguably been more reliable than the expensive Polymerase Chain Reactions (PCRs) invigilated by clinicians. LFTs have yet to be responsible for an incident as grave as that at the Immensa laboratory. 

The UK Health Security Agency shut the firm down in October, reporting that it had wrongly informed around 43,000 people that their PCR tests were negative, directly resulting in at least 400 deaths.

LFTs can be slower to pick up an infection in its early stages, and there is some evidence to suggest that this problem may be increasing with the evasive Omicron variant. 

Lateral flow tests work by containing antibodies in the test paper which will combine visibly with coronavirus proteins. PCRs detect genetic material, RNA, from the virus. Usually, this material does not reach a peak until several days into the infection, so it is possible that an LFT would not detect it in the early stages whereas a PCR is more sensitive and might. 

Travellers from abroad have to book PCR tests in advance – but they are in short supply with the result that many people are being prevented from coming home for Christmas. Domestically NHS procedure means that people do not get access to a PCR until they have tested positive with an LFT – so it is moot which is the best detector. 

LFTs have also picked up infections when people have been asymptomatic or not displaying the UK’s official symptoms for Covid. In the view of many, this list is long overdue for an update. 

Tussell, the independent analysts of government spending, told us that they have identified more than a thousand contracts to supply the UK with tests and related lab services at a total cost of £15.7bn. Users will have noted that many of the test kits are made in China.

While UK based firms accounted for £11.2bn of the orders, the largest single supplier is California-based Innova with £3.7bn worth of business.

One study found that Innova kits were 91 per cent accurate, though more widely it seems that LFTs are around 70 per cent accurate identifying initially infected people, increasing in the first week as the level of virus rises.

This level of accuracy suggests that LFTs have been relative value for money compared with some other measures against Covid, such as Dido Harding’s tracing white elephant, although some will quibble at the profit margins of suppliers.  

Most of us have found LFTs useful. Even when the test results are bad they can also be the first indicators of recovery. 

There will always be some cry-babies. Donald Trump did not enjoy his first swab tests: “I was a victim of the first test, meaning I had to go through it … I didn’t like what was happening … I called it an operation, not a test … They go up your nose and hang a right at your eye.” 

The Vice President and Second Lady complained that tests had been “invasive”. This earned them all an expletive-laden Twitter rebuke from the celebrity model Chrissy Teigen which I won’t repeat here in Christmas week. It was something along the lines of if they want invasive, they should see how childbirth had left her body. 

Most of us see the gain from the brief pain of an oral and nasal swab. For helping to protect us, I nominate annoying Lateral Flow Tests as The Objects of The Year 2022.