More PCR tests necessary for accurate diagnosis


Kathmandu, May 26

A woman, who tested positive for coronavirus infection and was undergoing treatment at Tribhuvan University Teaching Hospital, tested negative twice in the rapid diagnostic test. However, she tested positive for the infection in the polymerase chain reaction test in the National Public Health Laboratory.

Three of the five persons, who were admitted to Seti Provincial Hospital, tested negative in the rapid diagnostic test, but later tested positive in the PCR test. All three have been discharged from the hospital after recovery.

A female who had recovered from the infection after she tested negative twice in the polymerase chain reaction test, tested negative in the RDT after recovery. “A person who tests negative after recovery will have his/her antibody positive. This has posed a question on the efficacy of the RDT test kit that we are using,” said a doctor on condition of anonymity.

“If we are to prevent the infection from spreading, the government must immediately check the validity of our testing kits,” said the doctor.

Health experts have been raising questions on the validity of the rapid diagnostic test the government has been using.

“In the sensitivity test conducted in a laboratory outside the Capital in samples that tested positive for antibodies in the RDT method, only five samples tested positive for the respiratory contagion. The rapid diagnostic test must be used for large samples to find out sensitivity. But such validation has not yet been done,” said another health expert on condition of anonymity.

The government has conducted 97,967 tests using rapid diagnostic testing kits while it has conducted 54,424 tests with the PCR method.

The government has been repeating the polymerase chain reaction method if a person tests positive in the rapid diagnostic test.

The government has decided that the public can undergo RDT test for coronavirus. Also, it has said that people entering Kathmandu must come up with negative RDT test result.

“Both the decisions of the government are useless. The RDT test kits we are using do not tell us about the phase of infection. We are missing positive cases. As many of our cases are asymptomatic, there are high chances of infection spread in the community if we rely on RDT test kits. The government should test a large number of people using the polymerase chain reaction method. The idea is to test, trace and treat people,” said Dr Ashesh Dhungana, head of chest unit Bir Hospital.

“The RDT should be used only for surveillance. People should undergo PCR test as it is more sensitive and accurate than RDT. Anyone who tests negative in the RDT method but has the coronavirus will spread the infection in community,” said Dr Shravan Kumar Mishra, virologist at National Public Health Laboratory.

“The RDT test kits give positive result only after the seventh day of infection. RDT should not be used for clinical decision and it is not a correct approach. Blanket testing of blood samples using RDT is not reasonable,” said Dr Dhungana.

Despite questions on the sensitivity of RDT kits, the government has decided to procure 121,000 rapid diagnostic test kits. “The procurement process has already started.

The kits will be available in a few days,” said Bhogendra Dotel, director Management Division, under the Department of Health Services.

“To conduct a PCR test we need skilled manpower, wellequipped laboratory and the test is expensive. It is not possible to conduct PCR tests everywhere across the country.

But RDT test kits are cheaper and can be used immediately to test a large number of people. The objective of RDT is to find out whether or not there are cases in the community,” said Dr Samir Kumar Adhikari, assistant spokesperson at Ministry of Health and Population.

A version of this article appears in e-paper on May 27, 2020, of The Himalayan Times.

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