How accurate is the Covid-19 rapid antibody test?

The antibody testing at Atlantic Clinic is currently using the Acro Biotech kit.

The American supplier quotes an accuracy rate for the 2 types of antibodies: 

IgM: 92.9% IgG: 98.6%*

However, there are some uncertainties at the moment:

  1. These figures are based on current information. New data is coming in all the time and may refine them.
  1. The usefulness of the test depends to a certain extent on the proportion of people within a given population that has the virus, which is at present unknown. No one knows how many people may have been infected but show no symptoms.
  1. Antibodies take at least 7 days after infection (or after 4 days of symptoms) to show up on the test, so it is not useful in the very early stages of an infection. In these circumstances, where active Covid-19 is suspected, the PCR test is better, which in Spain is normally done in hospitals.

Antibody testing is used to identify those who have been infected for at least 7 days, or have recovered from a previous illness (either with symptoms, or a “silent infection” which went unnoticed). 

*For the technically minded, accuracy is a function of:

Relative specificity IgM 96%

Relative sensitivity IgM 85%

Relative specificity IgG 98%

Relative sensitivity IgG 100%

 

 

Dr. Anthony Crichton-Smith- GP

 

 

 

 

Categories: COVID-19
Post by: Atlantic Clinic on 23 Apr 2020