Sunday 25 October, 2020

Cayman: COVID-antibody tests reveal a 2.5% positive rate

The number of antibody tests that have been conducted at the Health Services Authority and Health City Cayman Islands now stands at 2,557 with 63 total positives -- a 2.5 per cent positive rate.

25 tested positive for antibodies without having ever received a positive PCR test.

Of the 63 positive antibody tests,

  • 38 were people who previously tested positive on a PCR test;  
  • 6 were contacts of previous PCR positive people;
  • 8 had a travel history abroad during the recent months; 
  • 11 had no identified COVID-19 contact history.

The Chief Medical Offier, Dr John Lee will not be reporting antibody test results going forward although the results will continue to be collected.

This is probably a good idea.

According to a June review reported in the Cochrane library on the diagnostic accuracy of antibody tests for the detection of infection with the COVID-19 virus, which is based on 38 separate antibody test studies, between 2 and 21 per cent of antibody tests can show false positive results-- and timing is critical.

The review shows that antibody tests could have a useful role in detecting if someone has had COVID-19, but the timing of when the tests are used is important and that after 3-weeks post infection, the results become unreliable.

Acording to the CDC, we currently don’t have enough information yet to say whether someone will definitely be immune and protected from reinfection if they have antibodies to the virus.

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