Many studies of COVID-19 antibody test accuracy fall short

Many studies of COVID-19 antibody test accuracy fall short

Many studies of COVID-19 antibody test accuracy fall short

"COVID toes" might not be a symptom of coronavirus infection, but instead the result of lifestyle changes during lockdown, two small studies published Thursday by JAMA Dermatology found.

"What our analysis has most clearly shown is that this [variations in the accuracy of tests from different studies] is largely driven by when the samples are taken from the patients", said Deeks.

They found that all tests showed low sensitivity (the ability to detect disease) during the first week after symptoms (detecting less than 30% of cases of disease), rising in the second week and reaching their highest values in the third week. Earlier, it was established that surfaces with an ability to carry COVID-19 can pose a danger to people who come in contact with them.

However, in all 31 patients, SARS-CoV-2 RNA remained undetectable in nasal and throat swabs and in biopsy samples of the skin lesions, the researchers said. However, when the researchers looked at data reported at between 15 and 35 days after symptoms first began, antibody tests accurately detected over 90% of people with COVID-19.

A blood sample sits on a table at an antibody testing program at the Hollymoor Ambulance Hub of the West Midlands Ambulance Service, operated by the West Midlands Ambulance Service NHS Foundation Trust, in Birmingham, Britain June 5, 2020.

There is intense interest in these antibody tests, which rely on either a finger prick or a venous blood draw, by people eager to know whether they have had COVID-19 or not.

Deeks said the use of tests in hospital settings might improve understanding of how Covid-19 spreads in hospital and take action, for example around personal protective equipment, but offers limited benefits on an individual basis.

807 people would receive a negative test result but 17 (2%) of those people would have COVID-19 (known as false negative result). The researchers were able to identify a unique pattern of six molecules, a discovery that could allow for targeted treatment.

In a population where COVID-19 was more common there would be more false negatives and fewer false positives.

Scientists examined the environment and air in the wards of 13 COVID-19 patients who returned from overseas and were placed in an isolation ward. The tests do not work accurately when administered at the wrong time.

The Spanish researchers behind one of the studies now theorize that "these skin lesions are not induced by the virus, but by the quarantine state itself". Many papers included multiple samples from the same patients. In one important United Kingdom study the biomarker manufacturers did not approve the identification of the tests that had been evaluated.

But now, the findings in the new study has come up with new results.

Another study, this time led by researchers in Belgium, conducted a similar study into purplish-red chilblain-like lesions on the feet (29 patients) and hands (three patients) of individuals seen at a Brussels dermatology clinic in April.

"This is a fast-moving field and we plan to update this review regularly as more studies are published".

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