Differences between the PCR and the Rapid Covid-19 Antigen Test

The new Omicron variant brought with it a large increase in cases of Covid infections, which raised alarms in the world.

It is important that the entire population become aware and go to the Covid tests if they have doubts about their health status. It is proven that an early diagnosis of the virus will make treating it easier.

Covid tests are within reach of the vast majority. They vary according to their execution and virus detection system.

The two main tests used to detect the virus are the PCR test and

SARS-CoV2 rapid antigen test , these have several distinctive features:

PCR test

This is a test in which samples are taken from the back of the nose and mouth using a swab, with which the presence of Covid genetic material (RNA) in the person will be detected.

What is recommended by experts is that this test be done on the third and seventh day after the onset of symptoms, this is because during this period of time there is more viral activity, so it will be easier to find the presence of the virus. However, it will also depend on what your doctor advises you.

This test is capable of indicating if the person is infected with Covid or with other pathogens.


  • High degree of confidence.
  • Diagnose the virus and the stage it is in.


  • Is more expensive.
  • Results may take longer.
  • It requires highly trained equipment and professionals that are not found in all laboratories.

Antigen test

 This type of test, according to the sample they collect, can be a Rapid Oral or Nasal Fluid Antigen Test. In its process, it looks for the protein of the virus that indicates that the person is or is not infected.

It is recommended that for maximum accuracy, it should be done about three days after the onset of symptoms, because on these days the patient’s viral load is lower and it is more difficult to detect the virus.

Its effectiveness is usually good whether it is a nasal test or a Covid-19 saliva test.


  • Less reliable than PCR
  • False negative rates.


  • Results in a few minutes.
  • Important for early diagnosis of the disease.
  • Cheaper and more accessible.
  • Easy to get and buy at pharmacies ( Covid-19 BOSON, Covid-19 NEWGENE, Covid-19 WESAIL, Covid-19 GOLDSIDE, Covid-19 FLOW FLEX ).

When to test for Covid 19

 You can access a SARS-CoV2 test when you prefer, be it molecular or antigenic, however, there are 3 specific situations in which you should not hesitate to do so:

  • If you present the symptoms of Covid, either all or some.
  • If you were in contact with a person who tested positive.
  • If you attended a very crowded place without the necessary biosecurity measures.

In conclusion, all the Covid 19 tests generally fulfill their purpose, but by having a different infection detection system, they provide more or less accurate results and in less or more time.