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Sri Lanka medical professional associations call for 1,500 RT-PCR tests per day

A resident wearing a facemask rides past the entrance of Sri Lanka’s Infectious Diseases Hospital near Colombo, where most confirmed cases are treated.

ECONOMYNEXT – Sri Lanka must increase its RT-PCR testing capacity to 1,500 tests per day, among other measures, to contain the spread of COVID-19 in the country, a collective of medical professional associations said.

The Sri Lanka Medical Association, the Ceylon College of Physicians and the Sri Lanka College of Microbiologists said in a joint statement issued today that community surveillance must also be conducted in identified hotspots.

“According to the epidemiology unit, currently there are 2,000 first level contacts in Sri Lanka. If these first level contacts can be covered through risk-stratified/pooled sampling, it will provide the evidence-base on how the next level of contacts should be screened, and address current concerns and uncertainty regarding the number of asymptomatic patients,” the statement said.

“In conclusion, we would like to emphasise that any shift of the current policy of testing for COVID-19 to be considered within the border framework of the present successful public health response and not as an isolated technical matter,” it added.

The primary strength of molecular tests, the medical collective said, is that they directly detect the gene sequences of the virus in the early stages of infection when the patient is infectious. Thus, detection of COVID-19 by RT-PCR (Reverse-transcription Polymerase Chain Reaction) can be done from five days prior to the onset of symptoms to several days after symptoms have waned off.

However, the statement hastened to add, no laboratory test is perfect.

“Although the test carries an almost a 100% specificity, these molecular tests can miss COVID-19 infections depending on the sample collected or if the patient carries a low viral load. The sensitivity is improved by repeating the RT-PCR tests.”

The three medical associations said the RT-PCR is preferred to IgG/IgM rapid tests.

“Detection of IgM/IgG antibodies to diagnose COVID-19 infection has been discussed in length in many meetings at local and national level. Advantages such as ease of testing, availability of results within a shorter time and possibility of using as a point of care (PoC) test have been cited by the proponents. However, this test cannot replace the value of RT-PCR test in the acute diagnosis of COVID-19,” the statement said.

IgG/IgM rapid tests rely on the detection of antibodies and patients may take up to 7 to 12 days to produce antibodies to COVID-19 infection. Therefore, the statement said, patients in the early stages of the disease will be missed if rapid serological tests are used for diagnosis. It will also lead to more spreading within the community due to false assurance depending on a negative IgG/IgM test result, it warned. Further, elderly or immunocompromised patients may never (or only much later) develop antibodies to COVID-19 infection.

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These IgG/IgM rapid antibody tests in paired samples could, however, aid in the diagnosis in cases that are highly suspected of having COVID-19 infection but a negative PCR test. According to the statement, these tests help in detecting unrecognised past infection and immunity for retrospective assessment of the attack rate or extent of an outbreak.

“However, it is not the current need of the country as far as suppression of the spread of the disease is concerned. Introducing a widespread screening test that is not sensitive and becomes positive late in the course of the disease is not compatible with the unique preemptive policy of Sri Lanka, which has been proven to be successful so far,” the statement said.

If such a method is adopted, the associations warned, it may convey a misleading message to the public, hindering the current efforts of the government to curtail the spread of the virus and community participation. (Colombo/April6/2020)

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