COVID-19 antibody tests - at least, those on the market through April - had a window for accuracy of only a few weeks after symptom onset, and little reliable data beyond that point, a Cochrane review found.
The National Institute of Allergy and Infectious Diseases (NIAID) recently published a review of a workshop conducted in May, which reiterated that serology testing should not be a stand-alone clinical decision-making tool, and that more research is needed about what a positive antibody test means in terms of risk for reinfection and immunity. The analyzed studies looked at almost 16,000 blood samples, 89% of which had a high risk of bias because patients were unlikely to match the general population.
Sir John Bell, Regius Professor of Medicine at Oxford University, who has been overseeing the government's antibody testing validation and strategy, said: "We've really set the gold standard in what you need to expect from these tests and I suspect a lot of people will be really interested in what we have produced in the last couple of months".
The NHS has been pushed to the brink due to the Covid-19 pandemic and the experts claim that this push to introduce non-evidence based tests is an "inefficient use of scarce resources".
"With the introduction of antibody testing, in addition to the PCR testing and all modalities of treatment, the Cayman Islands has the complete package in detecting and fighting COVID-19", he said. Most antibody tests measure both IgG and IgM, but some measure a single antibody or combinations of the three antibodies.More news: Blackpink Breaks BTS' YouTube Premiere Record With 'How You Like That' Video
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.
Pregnant women with COVID-19 are 50% more likely to need intensive care and 70% more likely to be put on mechanical ventilators than non-pregnant women, although pregnant women did not have a higher risk of death, CDC researchers reported in the agency's Morbidity and Mortality Weekly Report.
The researchers discovered that all antibody tests showed a low ability to detect the disease during the first week after symptoms, rising in the second week, and reaching their highest values in the third. The tests only wrongly diagnosed COVID-19 in 1% to 2% of people without COVID-19. "Until we learn more, no one should consider themselves immune to COVID-19 infection based on these results".
In a review of 54 available studies through the end of April, mostly from China, the accuracy of pooled results for combination immunoglobulin (Ig) G/IgM tests was 91.4% (95% CI 87.0-96.6) for 15-21 days post-symptom onset, reported Jonathan Deeks, PhD, of the University of Birmingham in the United Kingdom, and colleagues. However, it is not known at this time how long the body will have antibodies or whether they actually give immunity to future infections from this virus.
The researchers examined all available test accuracy evidence for antibody tests that have been published up to the end of April, finding that the tests are not accurate enough to confirm whether someone has the COVID-19 virus if used in the first two weeks after symptoms appear.More news: New Delhi on high alert after desert locusts swarm through neighboring Gurgaon
NYC Health + Hospitals will now offer free antibody testing for New Yorkers at its 11 acute care facilities for New Yorkers who have not had COVID-19 symptoms or a positive COVID-19 tests within the past two weeks.
The researchers also had several concerns about the quality of the studies they found. Studies were small and did not report their results fully. Many papers also included multiple samples from the same patients and more than half were made available before they had been through peer review, they said.
"For numerous studies, we could never find out how many patients were included in them", he said.
Dr Jac Dinnes, who worked on the review with the University of Birmingham team commented, "The design, execution and reporting of studies of the accuracy of COVID-19 tests requires considerable improvement".
The authors noted that the main results of the review are from 38 study cohorts out of 54 that stratified results by time since symptom onset.More news: MS appears to have votes to change flag, lawmaker says