KOCHI: Fighting the Covid-19 pandemic has been a stressful process for everyone. But this 47-year-old sanitation worker, who has been on the frontlines for the past six months, is probably one of the few who have had it worst. Viji Kumar, who was in one of the primary contact lists took two different Covid-19 diagnostic tests—RT PCR and antigen—on the same day. He was relieved when the antigen test came negative but had the shock of his life when the PCR test result came positive on the third day. By then, he had come in contact with many people, including his own family members.
“I have been a sanitation worker at the corporation for the past five years. I was stationed at the CFLTC in Green Field Stadium for patient transportation. Recently, one of the junior health inspectors tested positive and I was one of his primary contacts.
Following the instructions from higher authorities, I gave my swab samples at Fort Hospital for Covid testing. Later that day, I took the antigen rapid test at the Corporation’s main office. My result was negative and I got back to routine. On Sunday, I got a call from a police officer, inquiring my whereabouts. Soon, I received another call from the collectorate informing me that I am Covid-19 positive,” said Viji Kumar.
According to experts, the antigen test, which is the most common test for Covid-19, is only good for mass screening. Further, suspected patients with symptoms should take the RT-PCR even if their antigen test results come out negative. They must also stay in quarantine until the results come.
One of the core members of the State’s Covid-19 task force, Dr Mohammad Asheel confirmed that RT-PCR is the gold standard test. He added that the sensitivity of both these tests differ and there is no test in the world that is 100 per cent fool proof.
“We have deployed the antigen test as a cluster management strategy. Compared to RT-PCR, the antigen test has a higher chance of error. The antigen is more practical for cluster containment. We will get the result within 30 minutes. If symptomatic patient test negative in an antigen test, we make them do RT PCR,” he said. Compared to a patient with symptoms, the asymptomatic one has very little chance of infecting others, said the doctor.
As per current testing guidelines in Kerala, antigen tests will be carried out on all symptomatic individuals with an objective to detect cases early. Those testing positive in antigen tests shall be considered positive and those negative on antigen will be retested. And for those working in the frontlines including sanitation workers and health care workers, RT-PCR is the recommended testing method.
“Healthcare workers, sanitation workers and everyone who are exposed directly should do RT-PCR test and antigen test. Currently, because of the increasing caseload, the antigen test is more practical. Ensuring strict quarantine for everyone who has been exposed is the only sure way,” said an official.
Strict quarantine protocol is being advocated by many. “The tests are not error-proof. That is one of the reasons why the state government has come out with strict restrictions, designating containment zones where there is a spike in cases. The primary objective is to ensure that people who are in the high-risk group strictly follow home quarantine. Currently, RT-PCR is being done on patients who require emergency surgeries and symptomatic patients in the high-risk category whose antigen test came out negative. But, 20 per cent of the antigen test tend to show false-negative results, while a small percentage of RT-PCR could be false positive,” said a senior official of the health department.
What is RT-PCR?
RT-PCR ( the real-time polymerase chain reaction) is the most commonly used test for Covid-19 screening. The PCR test picks up the outside coat protein of the virus and is done by collecting a swab sample from the person’s throat or nose. It normally takes 8 to 12 hours to get the result.
What is an antigen test!?
The test is designed to detect a specific protein in the virus and the test picks up the part outside the virus. Antigen kits have low sensitivity ranging from 50.5 per cent to 84 per cent. The test provides results rapidly, within 15 -30 minutes.
Guidelines
As per current testing guidelines in Kerala, antigen tests will be carried out on all symptomatic individuals with an objective to detect cases early. Those testing positive for antigen tests shall be considered positive and those negative will be retested.