DOH studying coronavirus test using saliva

ABS-CBN News

Posted at Aug 24 2020 12:37 PM

Navotas City residents undergo nasal swab testing at a gymnasium behind the city hall on Aug. 20, 2020. George Calvelo, ABS-CBN News/File

MANILA -- The Department of Health said Monday it was studying a test for the novel coronavirus that examines saliva instead of nasal and blood samples. 

Japan in June approved the use of a polymerase chain reaction coronavirus (PCR) test using saliva, which is reportedly safer and easier compared to the currently dominant method that collects mucus from back part of the nose. 

“It is still being studied if it’s going to be feasible and acceptable here in our country, on how we are going to make use of it also,” said Health Spokesperson and Undersecretary Maria Rosario Vergeire.

There’s “not a lot of data on how long the virus is in saliva,” Dr. Kimberly E. Hanson, a testing expert at the University of Utah Hospital, earlier said, as quoted by The New York Times.

Also, “saliva is bubbly and hard to pipette.” As a result, labs are reporting 3 percent of tests invalid, compared to 1 percent for swab tests, “which is frustrating,” she said. 

The DOH has consulted medical societies and local governments, and will release guidelines the proper use, perks and disadvantages of tests like the real time PCR, antigen, rapid antibody and pool screening, said Vergeire. 

“We are just trying to finalize based on all of the comments we gathered through our consultation and within the week, we are going to release the omnibus guidelines,” she told ANC. 

In a pool test, specimens are grouped by 10 or 20 and undergo one PCR test. If one specimen yields a negative result, all the specimens in that batch are deemed negative, testing czar Vince Dizon earlier said.

But if one tests positive, the pool will be halved and tested again. This step will be repeated, further shrinking the pool, until the test identifies the sample that produced the positive test result, he added. 

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The RT-PCR test is considered the gold standard in coronavirus screening, while some doctors have discouraged the use of antibody tests that supposedly gave false results half of the time. 

Antibody tests are different from antigen tests, which look for a protein on the surface of the virus. They are not considered highly accurate but give results in 15 minutes, reported The New York Times. 

The Food and Drug Administration has approved 2 antigen tests, but the Research Institute for Tropical Medicine has yet to validate these, said Vergeire.

“We have to wait for that before we can use this,” she said. 

-- With reports from Kyodo News; The New York Times and Jamaine Punzalan, ABS-CBN News