Coronavirus: Volunteers wanted for antibody test trials

Coronavirus: Volunteers wanted for antibody test trials

"Placement of COVID-19 patients in rooms with negative pressure may bring a false feeling of safety, and rigorous environment cleaning should be emphasized", study author Dr. Zhiyong Zong, from the Department of Infection Control at West China Hospital, said in a journal news release.

Where around half of employees may have had Covid-19 - such as in health care settings - the researchers estimated that there will be seven false positives and 43 false negatives for every thousand people undergoing combined IgG and IgM testing 15 to 21 days after Covid-19 symptoms appeared. The tests were better at detecting COVID-19 in people two or more weeks after their symptoms started, but we do not know how well they work more than five weeks after symptoms started.

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. There were not enough data to compare the accuracy of different tests. "In time, we will learn whether having previously had the infection provides individuals with immunity to future infection, which will indicate the personal value of having this test".

"It is already very clear from this analysis that antibody testing early in the course of disease is unreliable and thus antibody tests can not, and should not, replace virus detection for diagnosis of acute cases except where the time-course of disease is already well advanced", she said. Tests of the IgG and IgM antibodies at 8 to 14 days after onset of symptoms correctly identified only 70% of people who had COVID-19. There are insufficient studies to estimate the sensitivity of antibody tests beyond 35 days after the beginning of symptoms. They found that inflammation profiling was able to predict the presence of COVID-19 in critically ill patients with 98 per cent accuracy.

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. The tests only wrongly diagnosed COVID-19 in 1% to 2% of people without COVID-19.

Employers hoping to get more staff back to work by using coronavirus antibody tests have been warned that they could miss one in 10 cases of Covid-19.

The researchers also fear accuracy will be lower when tests are used in the community, as the tests have mostly been evaluated in hospitalised patients - making it unclear whether they can detect lower antibody levels associated with milder and asymptomatic COVID-19 disease.

"COVID toes" has been described as "purplish-red lesions on the feet", according to the researchers involved in the studies.

"Our tests are safe and available now; waiting for the ideal solution will deprive employers of an important tool in ensuring the UK's economic recovery and so carries serious economic risks".

But now, the findings in the new study has come up with new results. The study is published this week in Critical Care Explorations. Action is needed to ensure that all results of test evaluations are available in the public domain to prevent selective reporting.

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