Positive vs reactive, what is the difference?



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Jakarta

There are many terms about COVID-19 that are confusing, including rapid antigen test results. In some places the results were expressed as “positive” or “negative” and in other places they were termed “reactive” or “non-reactive”.

So far, ‘positive’ or ‘negative’ results have been obtained from the PCR test (Polymerase chain reaction) or PCR swab. Meanwhile, ‘reactive’ or ‘non-reactive’ results are obtained from the rapid test, in this case the rapid antibody or serology test.

Is the rapid antigen test positive or reactive? Negative or non-reactive?

This rapid antigen test is unique. Unlike most rapid tests that detect antibodies or traces of an immune response, this type of test detects antigens, which are the genetic material of the virus itself. Therefore, the results are more like PCR tests. Sampling is similar to PCR, using a nose or throat swab.

“The antigen test is directly the virus that is being sought. Then it is more precisely positive or negative. Like PCR, PCR detects the genetic material of the virus so it is not its shadow (antibody)”, explained the biologist molecular Ahmad Rusdan Handoyo Utomo, on Thursday (12/24/2020).

BNPB2020 infographicThe difference between rapid antigen test and rapid antibody test. Photo: detikcom

So why is it called a rapid test if it looks more like a PCR test and how does it work differently from a rapid antibody test? Rapid refers to the examination process that is faster than the PCR test. If the PCR test takes hours, the rapid antigen test only takes 15 minutes.

In some countries, the term “rapid” in rapid antigen testing has begun to be dropped to distinguish it from rapid antibody testing. In fact, this type of test is expected to become the standard test for the diagnosis of COVID-19, like the PCR test, although the sensitivity is certainly lower than the PCR.

If the terms “reactive” and “non-reactive” in a rapid antibody test, what do they mean?

First, it should be understood that the rapid antibody or serological test does not detect the virus directly, but the response of the immune system, that is, the antibodies. The results obtained do not directly indicate the status of the infection, but a history of whether someone has been infected or not.

“So the antibodies are a history, when this person has been exposed or has never recovered, it detects the history, that is, the antibodies, so it is called to react or not to react,” Ahmad explained.

In conclusion, the result of a rapid true antigen test is indicated as “positive” or “negative” and not as “reactive” or “inactive”. I’m not confused anymore, am I?

Watch video “See the rapid antigen test process, which is a travel condition
[Gambas:Video 20detik](Up Up)



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