Asymptomatic COVID-19 Patients also Increase Contamination in the Environment

There were more problems, Cochrane said, including often no mention of whether the samples were anonymized or blinded, potentially leading technicians to repeat tests if they thought they had got the wrong result.

The immune system of people who have COVID-19 responds by developing proteins in the blood called antibodies that attack the virus. 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.

Specialists took samples from surfaces and found that 44 of 112 surface samples (39.3%) contained SARS-Cov-2 coronavirus.

"For numerous studies, we could never find out how many patients were included in them", he said.

The results suggest that isolation of asymptomatic COVID-19 patients at home may put their families at risk, and that shelter hospitals may be a better option, the authors said.

Led by experts at the University of Birmingham, a group of researchers drawn from universities around the globe have published their findings in the Cochrane Database of Systematic Reviews.

Professor Jon Deeks, Professor of Biostatistics and head of the Test Evaluation Research Group at the University of Birmingham, explains: "We've analyzed all available data from around the globe-discovering clear patterns telling us that timing is vital in using these tests". Most admitted to a largely "couch potato" lifestyle during that time, and "most patients declared that they remained barefoot or in socks during that time".

"There are promising tests, but there isn't enough evidence to be able to identify the best tests yet, and we need to continue analysing data as it becomes available - particularly from non-clinical settings where individuals are displaying less severe symptoms, and following people over longer time periods".

They drew blood from the patients daily for the first seven days of ICU admission, processed the samples in a lab, and then analysed the data using statistical methods. Detecting antibodies in people's blood may indicate whether they now have COVID-19 or have had it previously. For most patients, there is no out-of-pocket expense for antibody testing. Levels of antibodies rise and fall at different times after infection, with the IgG antibody usually highest a few weeks after infection.

Data were available on both laboratory based tests, which require blood samples taken from the veins, and point-of-care tests, which can use finger-prick blood samples.

A number of the rapid response kits are to be studied, including one from a consortium including Oxford University. In total these studies reported almost 16,000 test results. It also is not a test appropriate for anyone experiencing coronavirus symptoms.

The studies showed that the combination of IgG or IgM had a sensitivity of 72% for eight to 14 days; 91% for 15 to 21 days; and 96% for 21 to 35 days. Results are generally available in two to five days.

Volunteers will be recruited who have tested positive for the virus previously, alongside those who have tested negative.


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