Covid-19: Timing is critical for antibody tests, finds Cochrane review
A Cochrane systematic review has found that, when it comes to antibody testing for covid-19, timing is everything.
The review of 54 studies found that antibody tests carried one week after a patient first developed symptoms detected only 30% of people who had covid-19. Accuracy increased in to 72% at two weeks and to 94% in the third week.
“If you use them at the wrong time they don’t work,” said Jon Deeks, professor of biostatistics at the University of Birmingham and the review’s lead author.
The duration of rises in antibodies is also currently unknown, and the researchers found very little data beyond 35 days after the start of symptoms. Another problem is that the data mainly came from hospital patients, so it is unclear whether the tests are able to detect the lower antibody concentrations likely seen with milder and asymptomatic covid-19.