False negative COVID-19 test rate is about 30%. This is according to Specialist Family Physician, Dr Marina Klokke.
Klokke says, “The false negativity rate is approximately 30% or one in three, which is quite high, that why it very important for any person administering tests, whether it’s the antigen test or the PCR test to also adequately inform and educate the patient that there is a chance of a false negative.”
SABC News spoke to some people who have tested for COVID-19 and were confused that they received a false negative result.
According to the National Health Laboratory Services (NHLS), a false negative usually happens when the specimen or the sample that was summited was not of adequate quality.
Dr Marina Klokke elaborates on the false negativity rate:
Klokke says a false negative test happens for a number of reasons.
“Number one it has to do with your technique of taking the swab, so was the swab taken in the proper manner ? Then was it stored in the proper manner at your practice or at your hospital wherever the swab was taken ? They have to be kept cool, where they transported in the appropriate manner ? We saw during the first wave, when labs where completely over run that there was a delay in up to a week to actually process those tests and many of those tests degenerate after a certain amount of time.”
She says the timing of the test is important because if you do the test too early after exposure and infection, the person is likely still get a very low viral load because they have not had sufficient viral replication to have built a significant viral load.
INFOGRAPHIC: What causes a false negative COVID-19 test?
In this audio, Virologist at the Nation Health Laboratories Service, Dr Florette Treurnicht explains in detail what a false positive test is:
‘Testing was very efficient’
A man from Johannesburg, who chose to remain anonymous says he received a false negative COVID-19 test after testing at the Sandton Mediclinic.
“Testing was very efficient, I went to Sandton Mediclinic, they have a testing centre in the parking, Lancet Labs runs that facility. I had a note from my Dr to go get tested, as I presented symptoms of COVID-19, a dry cough, wheezing cough, and a heavy chest. My test had come back negative.
Anonymous says he went to go test after he came into contact with a person that tested positive for COVID-19 at work.
“There were people at our offices that had presented with positive tests, and I may have possibly been infected that way.”
He says because he had recurring symptoms, went and tested again and the results came back positive.
“So that is the thing, some are saying I may have tested too early or too late. It was about five days into the symptoms. I guess the moral of the story here is that even if you test comes back negative and you present with symptoms of COVID-19, isolate and seek further medical help.”
INFOGRAPHIC: Types of COVID-19 tests: