PH to expand use of antigen tests depending on Baguio pilot study

Kristine Sabillo, ABS-CBN News

Posted at Oct 16 2020 07:22 PM | Updated as of Oct 17 2020 03:43 AM

MANILA — While it has already released its Omnibus Guidelines for testing and other COVID-19 response strategies, the Department of Health on Friday said it is still looking at other uses for antigen testing.

In the DOH memorandum 2020-0439 or the Omnibus Interim Guidelines on Prevention, Detection. Isolation Treatment, and Reintegration Strategies for COVID-19, antigen tests are only allowed to be used in areas where there is limited polymerase chain reaction (PCR) test capacity, when quick turnaround time is needed and for quicker case finding for community outbreaks.

Originally, the Philippine government wanted to use it for screening in airports but the World Health Organization later issued guidelines saying it is not appropriate for border screening.

“Ituloy natin yung Baguio pilot study so we can appropriately determine kung ano itong rational use ng antigen for us, aside from the WHO recommendation,” Health Undersecretary Maria Rosario Vergeire said during a virtual briefing. “Baka pwedeng tignan natin doon pa rin sa ibang sectors natin like travelers (tulad ng) sinusubukan natin ngayon sa Baguio.”

(We’ll continue the Baguio pilot study so we can appropriately determine the rational use of antigen for us, aside from the WHO recommendation. Maybe it can also be used for other sectors like travelers like what we’re trying in Baguio.)

Vergeire said the problem with Baguio is that it only has 200 travelers tested using antigen test kits.

“It is not yet sufficient for a sample size. Kasi ang sample size na nakalagay sa protocol ng study is almost 1,000 (Because the sample size specified in the study protocol is almost 1,000,” she said.
“Kaya hindi pa conclusive. Hindi pa sufficient ang sample para makapagsabi tayo na ito na talaga ang resulta na basehan at ebidensya para gumawa tayo ng protocol,” she added.

(That’s why it’s not yet conclusive. The sample is not yet sufficient for us to say that this is the result and it can serve as a basis or evidence for a protocol.)

While waiting for more travelers to be tested, the analysis of antigen tests done in 2 barangays in Baguio where COVID-19 outbreaks were monitored is now being studied by experts.

Vergeire said the use of antigen tests specified in the Omnibus Guidelines is based on the recommendations of the WHO and the Health Technology Assessment Council.

“Kapagka lumabas na yung kumpletong resulta galing sa Baguio, dyan natin irerevise yung omnibus guidelines kung sakaling makita na pwede pang gamitin sa ibang sektor ng ating society,” she said.

(Once we have complete results from Baguio, we can revise the omnibus guidelines in case we prove that it can be used for other sectors in society.)

DOH also explained why Baguio is still using the antigen test from South Korean company SD BioSensor even after a study by the Research Institute for Tropical Medicine showed that it only has 71% sensitivity, lower than the requirement of 80%.

Vergeire said that after the RITM test, the WHO released its own emergency use list including the SD BioSensor antigen test.

She said this made RITM review the results of their tests.

“Yung WHO ang ginamit nya na basis ay yung pag-aaral ng diagnostic performance sa Germany. Kung saan ang diagnostic performance sa Germany lumalabas 76.6% ang sensitivity and in Brazil it’s another cohort 88.7%,” she said.

(The WHO used as basis a study from Germany where the diagnostic performance showed 76.6%. For another study in Brazil it was 88.7%.)

Vergeire said the RITM learned that the results vary based on the “cycle threshold,” which depends on the viral load of a patient.

“Ibig sabihin it directs us na meron talagang basehan na pwede mo naman gamitin ang antigen for specific circumstances,” she said.

(This means, there really is a basis for using antigen tests for specific circumstances.)