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05 April 2021

Bread, cheese, and Covid tests

Could you imagine the convenience of buying Covid-19 tests with your groceries? How wonderful would that be? To be able to go to school, work, and the pub normally and safely again? All thanks to a stubby little stick that quickly and reliably tells you whether you have the dreaded Covid.

Well, rapid tests are coming and will be stocked in supermarket aisles soon. In Germany they are already available. The high demand for the offer – five antigen tests for 25 euros – took down both Aldi’s and Lidl’s websites. And other countries will likely follow. In the Netherlands, for example, they have been approved and will become a reality in mid-April.

However amazing this might sound, we have some serious reservations about rapid self-testing.

To start with, self-testing sounds easier than it is. In practice, clear instructions or trained guidance are necessary. Simply fiddling around with the cotton wool stick doesn’t produce the reliable results we see in scientific research into the validity of antigen tests.

A half-heartedly taken self-test with a negative result can offer false security. The test says “No” and yet you can infect others: colleagues, teachers, loved ones...

The expectation is that there will be a flood of self-tests on the market. Naturally CE-marked and properly validated, but still, reliability will vary. Words like sensitivity and specificity are just gobbledegook to the average consumer. In practice, many people will have little or no idea what they are buying.

For example, do they know that you need *a lot of* virus particles to be present for the test to show a positive? If there are not quite enough of them to test positive, you will have Covid-19 – but the test will say you don’t. And do they know the test works best in the early stages of infection, and less well in people without symptoms?

The test that offers the best guarantee of accuracy is the PCR test – the “gold standard.” And if you want to cross a border, you can expect to do a PCR test, even if you have to wait a bit longer for the result.

With the advent of saliva and gargle tests, sample collection for PCR tests will hopefully become more pleasant. Research is ongoing. And you may soon be able to arrange your PCR test, test result, and traveller's declaration online from your couch. This may be the future: but unlike the antigen self-test, the PCR self-test is not coming to you this summer.

But with a little luck, it won't have to. Let's hope that with vaccinations, lots of testing, and above all *good quality* testing, we can stamp the virus out and move on with our lives.

Authors: Esther Talboom-Kamp, PhD, CIO Unilabs and CEO Unilabs Netherlands ad interim; and Maaike de Vries, PhD, strategic innovation consultant.