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Corona rapid test: how safe is self-sampling?
Photo: photonews.at/Georges Schneider / imago images / photonews.at
The first Corona self-rapid tests should be in the discounter in the coming days.
Health Minister Jens Spahn announced this on Wednesday in the ZDF morning magazine. How many tests will be available and how much they will cost is unclear.
One thing is certain: The first three rapid tests for laypeople are now approved in Germany, with more to follow in the coming week.
But how good are the corona home tests really?
Laboratory doctors are skeptical about the informative value of the tests and the approval process.
"We fear that if the rapid tests are incorrectly safe, people will no longer take the precautionary measures so seriously and that the infections will then increase again massively, especially because of the more contagious mutants," says Matthias Orth, chief physician at the Institute for Laboratory Medicine at Marienhospital Stuttgart, the SPIEGEL.
Austria is already relying on layman rapid tests in the fight against the pandemic.
Critics, including manufacturers, then complained that approval in Germany was taking far too long.
However, the Federal Republic of Germany put in additional safety nets when it was approved - and there is a reason for caution.
"Countless tests thrown on the market"
Because corona rapid tests are considered medical devices, they have to go through less strict approval procedures than those prescribed for drugs, for example.
The lax regulations have long been criticized (read more here).
The corresponding European directive for medical devices has been tightened.
However, there is a transition period until 2022. »At the moment, countless rapid tests are being thrown on the market.
There's a real gold rush atmosphere there, ”says Orth.
In Germany, there are minimum criteria that rapid tests must meet in order for the federal government to cover their costs.
The Federal Institute for Drugs and Medical Devices (BfArM) maintains a list of relevant products.
However, the state only pays if the tests are carried out by qualified personnel using the appropriate criteria.
Everyone will probably have to pay for lay tests.
In the case of professional rapid tests, information from the manufacturer is what counts
However, there is also criticism given the evaluation of the professional tests.
The BfArM can
only check whether the information provided by the manufacturer corresponds to the specified minimum criteria
.
"Such a comparison is certainly better than nothing, but the information comes solely from the manufacturers," says Orth.
He is suspicious of the fact that there are importers named “Luxus Lebenswelt GmbH” behind some products.
However, German authorities do not rely solely on manufacturer information.
The Paul Ehrlich Institute (PEI), for example, carries out independent reviews.
If a product fails, it is removed from the BfArM's list.
Additional requirements apply to the lay rapid tests.
Because unlike the professional rapid tests, they are subject to a special approval procedure, the BfArM announced at the request of SPIEGEL.
To be approved, they must meet certain requirements:
It is crucial that the product is
already approved for professional use
.
Applicants must have a corresponding CE mark.
And the product must
have withstood
testing by the PEI for professional users
.
In addition, the applicant must prove that the
product is also suitable for use by laypeople
.
This includes, for example, that there are instructions for use in German.
It has only been possible since February that such tests can even be given to laypeople.
The Ministry of Health had adapted a regulation specifically for this.
Since then, around 50 manufacturers have submitted applications for special approval for lay tests.
Why were these three tests approved?
"The test duration of special approval procedures depends to a large extent on the quality and completeness of the data submitted," said the BfArM at the request of SPIEGEL.
Approval has the highest priority and is going through a so-called "rolling review" process.
This means that the manufacturers can also submit the necessary data gradually.
In addition, the BfArM supported the manufacturers with the application.
"Nonetheless, the BfArM is not lowering the requirements for the reliability of these lay tests so that the tests are actually used safely by lay people and can make an effective contribution to combating pandemics," the authority continues.
How reliable are the lay samples?
According to the company, the Clinitest COVID-19 Antigen Self-Test from the manufacturer Siemens Healthineers, which belongs to Siemens AG, was tested on 50 people with no previous medical experience.
You carried out the test yourself using the instructions for use.
This confirms the practicability by laypeople, according to a press release.
The press release does not reveal whether one of the subjects tested positive or whether the results of the rapid test were compared with a PCR test.
A request from SPIEGEL about the details of the examination with laypeople to Siemens Healthineers initially remained unanswered.
It is crucial that samples taken by laypeople also deliver reliable results.
According to Health Minister Spahn, self-tests could provide security in specific situations.
For example, before going to the theater or the hairdresser.
However, the self-tests have a higher error rate than the PCR tests, the Ministry of Health announced at the request of SPIEGEL.
If a self-test turns out positive, you should
go to quarantine at home
as a
precaution
and have the
result confirmed by a PCR test
.
Rapid tests only provide sufficient security for a few hours
Orth fears the tests could be used for purposes for which they are not suitable.
Secure a weekend trip to the family with a quick test from the supermarket and do without distance rules?
Too risky according to the laboratory doctor.
Even the professional rapid tests only provided reliable results in symptomatic subjects or with a high viral load.
"The professional tests can probably fish out highly contagious infected people, but only in a very limited period of a few hours."
According to the manufacturer, the sensitivity of the Clinitest COVID-19 Antigen Self-Test is 97.25 percent, the specificity is 100 percent.
In an independent review, however, the sensitivity in the professional version of the test was lower.
The value indicates what percentage of those actually infected are also recognized as such.
In symptomatic Covid 19 patients, the sensitivity was a good 80 percent.
With asymptomatic only 60 percent.
Practical tests with other products have also shown that rapid tests are less reliable when infected people have no symptoms.
In an independent test by the Robert Koch Institute (RKI) of another professional rapid test, which is considered one of the most reliable, the sensitivity in asymptomatically infected people was only 40 percent.
The RKI therefore recommends professional rapid tests, especially
for short visits, for example in nursing homes
.
Those who have to be admitted to hospital for a longer period of time should better be tested using PCR or, according to the RKI, the rapid antigen tests should be repeated regularly, about every one to three days.
"If professional tests on asymptomatically infected people only have a sensitivity of 40 percent, it should be even lower when sampling by laypeople," says laboratory doctor Orth.
In Baden-Württemberg, visits to the hospital are already possible if a negative rapid antigen test is available up to 48 hours ago.
Orth thinks that is risky.
Even the manufacturer says: A negative test result does not release you from the AHA regulations
He also rejects the idea of testing yourself with a negative antigen rapid test in the event of an asymptomatic course from quarantine.
"That is not what the tests are made for," says Orth.
It makes sense to use it wherever people inevitably come together closely for a certain period of time, for example in schools.
But then the rapid tests would ideally have to be done every day.
“A self-test has to be absolutely foolproof.
If you don't do it properly, it can't deliver any results, ”says Orth.
Diabetes tests are a good example.
"If you don't do the test with blood or apply too little, the test won't give you a result." Orth warns that things are different with corona rapid tests for personal use.
"They can also give a negative result if I just hold them to the wind."
Siemens Healthineers, on the other hand, points out in the press release that the position and number of the lines indicate whether something was done wrong during the test.
But even the manufacturer emphasizes that the now approved layperson's quick test is only a snapshot.
The press release says: "A negative test result does not release you from the AHA regulations
(distance, hygiene, everyday mask; editor's note)
and other local safety measures that are currently in force."
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