What is the difference between COVID-19 antigen test and swab test
Superstar Amitabh Bachchan and his son Abhishek Bachchan, both tested positive for the highly infectious coronavirus on Saturday. Senior Bachchan was reportedly feeling breathless since the last couple of days and was admitted to Nanavati hospital on Saturday night. The veteran actor took to Twitter to inform the public about the diagnosis. He also urged everyone who had come in contact with him for the last 10 days to get tested. According to Nanavati sources, the actor is not on a ventilator, as of now. He wrote, “I have tested COVID-19 positive .. shifted to Hospital .. hospital informing authorities .. family and staff undergone tests, results awaited. All that have been in close proximity to me in the last 10 days are requested to please get themselves tested.”
Abhishek Bachchan has also tested positive
His son, Abhishek Bachchan has confirmed that he also tested positive for COVID-19 in a separate tweet and requested everyone ‘to stay calm and not panic.’ Junior Bachchan wrote, “Earlier today both my father and I tested positive for COVID-19. Both of us having mild symptoms have been admitted to hospital. We have informed all the required authorities and our family and staff are all being tested. I request all to stay calm and not panic. Thank you.”
Aishwarya and Aaradhya Bachchan have also tested positive
According to reports, the coronavirus antigen test of Amitabh’s wife and actress Jaya Bachchan, came out to be negative. However, Aishwarya Rai Bachchan and her daughter, Aaradhya Bachchan have tested positive for the contagion.
The difference between COVID antigen test, antibody test and swab test
It has been more than six months since the novel coronavirus started wreaking havoc across the world. As a result, the accuracy of coronavirus tests is slowly improving and currently, there are three major types of COVID tests, including antigen, antibody and swab test (RT-PCR). We are looking at all the three tests which are used to detect the presence of the highly contagious virus.
What is the swab test (RT-PCR)
One of the most common tests conducted to detect the novel coronavirus is the real-time polymerase chain reaction (RT-PCR) test. It is a highly sensitive test which helps with the early detection and onset of the novel coronavirus. It works by identifying the RNA traces of the coronavirus through a swab sample taken from a person’s nose or throat. It is a variant of PCR test which actually multiplies the genetic material of the pathogen taken from the swab to make a correct diagnosis.
In the reverse-transcription PCR, once the swab sample is taken, the RNA of the coronavirus is converted into DNA, so that virus particles can be detected and a fluorescent dye marks the presence of the virus.
Time taken by the test
This method of testing for novel coronavirus is said to be super sensitive and quick. The complete testing may take anywhere from four to eight hours, but keeping the time taken to transport the samples to the lab in consideration, it may take a day or two to get the results.
The drawback
On the downside, it only helps in detecting the presence of the virus at the time of taking the swab and cannot tell, if you have been infected in the past. Furthermore, if the swab sample is not taken correctly or if it doesn't have enough viral material on it, chances of a false negative increase. If you get tested immediately after exposure, there is a hundred per cent chance of getting a false negative, according to a study published in the Annals of Internal Medicine.
What is the antigen test
The antigen test is conducted by taking a swab from the nose to detect the presence of ‘spike protein’ which is present on the surface of the novel coronavirus. The nasal swab is then dipped in a solution that deactivates the virus. Post this, the solution is put on a strip which contains antibodies which bind to proteins present in the coronavirus. If the viral proteins are present, coloured lines will start emerging on the paper strip within 15 minutes.
Antibody test
An antibody vaccine test (also known as serology test) is used to detect antibodies in your blood against the novel coronavirus. This test helps in determining whether you have developed protective antibodies against the virus, in reaction to the infection.
This test does not look for active signs of the virus, rather it looks for antibodies which your body makes when you contract the infection. This test also helps to determine whether you were infected with the virus in the past, in case of no symptoms.
Sample for this test is collected by drawing blood from a vein of the patient. After this, the collected sample is tested for the presence of protective antibodies against the virus.
The biggest drawback of this test is that if you get tested too early after contracting the infection, your body may not have enough time to develop the antibodies. It may lead to the possibility of false-negative.
Benefit of antigen test
The test is rapid, hasslefree (when compared to the RT-PCR) test and gives results within 30 minutes. However, at the same time, it is not as sensitive as the RT-PCR test and may result in false negatives in case of insufficient viral particles in the swab. The underlying benefit is that if a person tests positive through the antigen test, a confirmatory RT-PCR test is not required to confirm the presence of viral particles.