Doctors divided over the testing of patients for COVID 19

Editors note – This article is re-posted with factual errors corrected

ECONOMYNEXT- Medical specialists in Sri Lanka are divided about the efficacy of the testing being done in this country to detect patients infected with the Coronavirus disease 19 (COVID 19).

The dispute is raging while the government health sector ramps up testing particularly of patients entering some 43 hospitals around the country.

In a recent Television interview, the President of the Government Medical Officers Association (GMOA) Dr Anuruddha Padeniya said only 70 out of 100 people who have the virus could be confirmed as the sensitivity of Polymerase Chain Reaction (PCR) test which is currently in use is found to be 70%.

Padeniya also points out that the World Health Organization (WHO) is now asking countries to do multiple tests to identify patients accurately.

This view is contested by Consultant Virologist Dr Jude Jayamaha of the Medical Research Institute.

Speaking to EconomyNext Jayamaha claimed that the “analytical sensitivity and specificity of Polymerase Chain Reaction (PCR) is 100% but the clinical sensitivity can differ depending on the patient, illness, quality of the sample and transportation of the sample.”

Jayamaha who is the Head of the National Influenza Laboratory of the Medical Research Insititute said that the Chinese study which is relevant to this statement was done on the
Detections of SARS-CoV-2 in Different Types of Clinical Specimens and it revealed that the nasopharyngeal swab positive rate is 68%.

“But it was wrongly interpreted saying that PCR sensitivity is 70% and it can miss 30%,” he added.

Further, he said based on suspicion they have retested over 100 samples even of the dead based.





For example, the husband of the Chinese women was retested as he was found negative in the first instance.

Regarding the two tests which are used worldwide to identify COVID-19 patients, through PCR the virus RNA or DNA, in other words, the genetic material of the virus can be directly tested in respiratory phlegm or respiratory swab.

The other test detects antibodies formed after the patient is infected are found in blood samples.

The PCR needs to be conducted by a highly trained medical technician.

“PCR is tested early in the disease whereas antibody is tested after some time, so to detect acute cases or control measures maybe it’s not the ideal tool,” Jayamaha said.

Jayamaha said even after 7 days or 14 days the PCR can detect the virus.

“The main obstacle of the antibody test is tests kits available in some markets are not sensitive,” he said. The Director-General of Health Services Dr Anil Jasinghe is on record as saying the antibody test kits that his department has received “cannot be validated.”

Other reports from the United States and Europe have said some of the Chinese supplied antibody tests were not reliable.

Also, regarding the patients who were found to be infected with COVID-19 after completing the general quarantine period, he said that there could be two reasons for finding infected patients beyond the general observation period of 2-14 days.

The first reason could be since everyone is together in quarantine centres and some stay for 7 days in centres after being self-quarantined for 7 days, those individuals can get exposed as they get on to the bus with the other patients, he said.

“The other reason could be the very rare possibility of going beyond 14 days to show symptoms,” he added.

Dr Jayamaha also said “According to the available data at present, a patient who is cured of COVID-19 would be immune to the virus since the virus RNA will be there in the cured patient and unlike hepatitis B there is no Chronic condition in this.”

But he added that this can change in the next ten days and the most accurate answer for this could be given in six months’ time. (Colombo/Apr14/2020)

Edited by Arjuna Ranawana

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