Research by the British non-profit organization Cochrane showed that antibody tests are best done 2-5 weeks after infection with coronavirus. If you make them earlier or later than this deadline, they may show the wrong result.

Cochrane Review reported that coronavirus antibody tests work best 2-5 weeks after the first symptoms of COVID-19. If you make them too sooner or later, they will not work.

This conclusion is supported by a review where the accuracy of antibody tests was thoroughly investigated. Cochrane researchers from universities around the world studied the 11,000 publications on COVID-19 that were available in late April to find studies that reported antibody test results in groups of people who had a confirmed diagnosis. In total, they found 54 relevant studies that reported test results on nearly 16 thousand samples. Most studies have been done in China in people who were hospitalized and probably had a serious illness.

Researchers have found that the sensitivity of an antibody test is related to when it is performed. Antibody tests 8-14 days after the onset of symptoms correctly detected them only in 70% of people who had COVID-19. However, when the researchers conducted tests between 15-35 days after the onset of the disease, antibodies were detected in more than 90% of patients. The researchers had too little data to assess the sensitivity of the tests, which were done 35 days after infection with coronavirus.

“We analyzed all available data from around the world, revealing clear patterns that tell us that using these tests, time plays a vital role. If you do the test out of time, it may not work. Therefore, we don’t know how accurately tests work in people when they were done too soon or too late”, the researchers explained.