There are now 3 types of Covid-19 tests available;

  1. PCR
  2. Rapid antibody tests for IgM and IgG
  3. ELISA antibody tests for IgM and IgG 

Confused?  Here’s what they mean:

 

1. PCR (polymerase chain reaction): 225€

(For 5 or more tests 195€/ person)

This detects the presence of genetic material from the coronavirus.

How?  Swabs (like a long cotton bud) collect mucous from the back of the throat and nose.

Time for result: at Atlantic Clinic 2 days.

When? The test shows positive early in the disease (within a couple of days after symptoms begin).

Why? 

  1. To diagnose the illness in the early stages of the infection, or;
  2. Increasingly some countries require a negative PCR test within 4 days prior to entry to avoid the 14-day quarantine period.

Limitations: 

a. After recovery the PCR may no longer be detectable so it is not so useful to diagnose a previous infection.

b. The PCR may persist for some time even after recovery because of residual genetic material leading to confusion over whether a patient is still contagious.

c. The test may be falsely negative if the sample is not taken correctly, or if the virus is not present in that part of the body (it may be only in the lungs, for example).

 

 

 

 2. Rapid antibody tests: 65€ 

(or for 5 or more tests 50€ /person)

This detects the presence of antibodies (the body’s defense against the virus) which are produced in response to the infection.

How? The sample is either a drop of blood from a finger prick or a blood sample taken from the vein. 

Time for the result: At Atlantic Clinic the result is ready within an hour.

When? Antibodies take at least 7 days from infection or 4 days from the start of symptoms to show up. The IgM antibodies are seen first as the disease progresses. After recovery, the IgM disappears and IgG persists.

Why? 

  1. It is the quickest and cheapest test.
  2. It is most useful for those who have had no symptoms, or symptoms some time ago, (a minimum of 4 days) and would like to know if:
  •  You have had the disease in the past and have recovered, or;
  • You are currently infected and what stage of infectivity or recovery you are in.

Limitations

Not useful for diagnosis in the early stages of the disease (PCR is better).

 

 

3. ELISA antibody test (enzyme-linked immunosorbent assay) 120€.

This also detects antibodies but uses more sophisticated techniques and needs skilled technicians. It may be more accurate than the rapid test.

How?  A blood sample is taken from the vein. 

Time for result: At Atlantic Clinic the result is ready within 4 days.

When? As with the rapid test, the antibodies take at least 7 days from infection or 4 days from the start of symptoms to show up. 

Why? It is often used to confirm a rapid antibody test result that is in doubt.

Limitations

  1. It is more expensive than the rapid antibody test and takes longer to get the results.
  2. Not useful for diagnosis in the early stages of the disease (PCR is better).

 

 

How accurate are they?

The manufacturers quoted accuracy rates for the methods used at Atlantic Clinic are:

PCR: Specificity and sensitivity 99.999%

Rapid antibody test:

– IgM specificity 96% and sensitivity 85%

– IgG specificity 98% and sensitivity 93%

ELISA: 

– IgM specificity 97.5% and Sensitivity 82%

– IgG specificity 97.3% and sensitivity 91.2%

Categories: Uncategorised
Post by: Atlantic Clinic on 28 May 2020