This post telling healthy people to stop getting tested is full of inaccuracies

A Facebook graphic has urged “healthy” people to “stop being tested” and listed a number of reasons why, including claims that 400,000 people being are being paid to be tested every week, 90% have no symptoms, that the government has “admitted” that 93% of positive tests are false, and that lockdowns will end when healthy people stop getting tested for covid.

There are numerous inaccuracies here.

Paid to be tested?

The source of the claim that 400,000 people are being paid to be tested is unclear. 

However, the figure aligns with targets for the expansion of the ONS’ Infection Survey. According to the Office for National Statistics (ONS), as of 8 October 341,534 people across 153,500 households in England are currently enrolled. 

It’s important to understand that this is not the same as the testing program that forms part of the national Test and Trace scheme, and which produces the widely reported daily figures for new cases. 

The survey’s purpose is to work out how many people in the general population currently have the virus, or have had it in the past, by measuring virus levels and antibodies.

People who participate in this study do receive a voucher each time they do, although not everybody enrolled in the survey is tested each week, so 400,000 people would not be paid “every week”. 

How many have symptoms?

The post claims 90% of people infected with the virus have no symptoms. There is currently no fixed figure for Covid-19’s asymptomatic rate, and reports on the subject have varied greatly. 

The 90% figure most likely comes from a recent study by University College London, based on data from the ONS Infection Survey, which found that 86% of people testing positive did not report one of the three main Covid symptoms (cough, fever, loss of taste/smell) on the day of their test. When including other symptoms (such as shortness of breath or fatigue) that figure fell to 76%.

It’s worth noting that the study only included 115 people with a positive result, and it only looked at whether they had symptoms on the day of the test, meaning it can’t rule out that they may have developed symptoms later.

It’s hard to know the true asymptomatic rate without testing every person, but there are some things we know about it. For example, children are reported to be more likely to suffer from lesser or no symptoms than adults. Overall, while we know that a significant percentage of infected people will experience mild or no symptoms, it’s hard to put a definitive figure on it, and the 90% figure may be too high.

False positives?

The post claims the government “admits” 93% false positives. A false positive is when someone who does not have the Covid-19 virus gets a positive test result. (Tests can also produce false negatives, where people who do have the virus are told they don’t.)

This claim likely refers to a quote from Foreign Secretary Dominic Raab, which he gave in response to a question about why the UK is not testing people on arrival at airports. We’ve written a fact check about this claim here. Mr Raab probably meant to say “false negatives”, not false positives, as he was referring to a Public Health England study that did not discuss false positives at all, and he was making the point that testing at airports could miss a large number of people who were infected.

No test is 100% accurate, and it’s hard to know the precise false positive rate for Covid-19 tests, but all the evidence suggests that the number is extremely low.

For example, as the ONS points out, their Infection Survey tested a large number of people over the summer, when the virus levels in England were low. Over six weeks between July and September, they tested 208,730 samples, of which just 159 returned a positive result, or 0.08%. 

Even if every single one of those was a false positive (which is unlikely) it still suggests that the false positive rate for the ONS tests can’t be higher than 0.08%—because if it was, there’d have been more than 159 positive results, regardless of how many people had the virus.

Likewise, the rate of positive tests from the Test and Trace scheme got as low as 0.9% at several points over the summer. (You would expect this level to be higher than the ONS survey, because unlike the ONS, Test and Trace doesn’t test people at random: it’s for people who have symptoms or may have been exposed to the virus, and therefore have a higher chance of truly being infected.) 

Again, that suggests that the false positive rate for these tests can’t be higher than 0.9%, unless something significant were to have changed about how the tests are conducted. There’s no reason to believe that it has.

False positives also cannot explain why the positivity rate has been rising sharply in recent weeks, with the most recent data (up to 7 October) showing that 6.3% of people tested got a positive result.

An end to lockdown?

As we have said before, fewer people getting tested will not make it look as though Covid-19 levels are lowering. There are numerous factors taken into consideration when measuring the virus’s prevalence among the population, and a lack of testing might lead to an extended pandemic.