City health authorities welcomed the issuance by the health department of the guidelines governing the use of the antigen test following the successful conduct of its pilot test in the city.
City Health Officer Rowena Galpo said the successful conduct of the antigen pilot test in the city led to the issuance of DOH Memorandum Circular (MC) NO. 2020-0468 dated October 26, 2020 prescribing the supplemental guidelines on the use of the rapid antigen test kits.
The guidelines were crafted, according to Galpo, following the recommendation of the World Health Organization (WHO), Health Technology Assessment Council (HTAC) and the results of the pilot testing on close contacts of confirmed COVID cases and travellers in the city.
Under the aforesaid guidelines, rapid antigen test shall be allowed for diagnostic testing of close contacts in communities and closed or semi-closed institutions with confirmed outbreaks and in settings where reverse transcription polymerase chain reaction (RT-PCR) is not immediately available.
For symptomatic close contacts, the rules stated that antigen testing can be used as a confirmatory test.
On the other hand, for asymptomatic close contacts, antigen testing can be used provided that the negative results are confirmed with RT-PCR or be subjected to repeat antigen testing within 48 hours after the first negative test results.
However, the use of antigen testing is not recommended in settings with expected low prevalence of cases or population with no known exposure, such as among asymptomatic travellers or for border control.
According to the rules, antigen tests are most useful during the acute phase of the virus when the viral load of the patient is high, which is within 5 days after onset of symptoms.
More importantly, the rules stipulated that a positive antigen test among close contacts is interpreted as a confirmed COVID case but for asymptomatic close contacts who test negative with rapid antigen test, the results of the confirmatory test, either through RT-PCR or repeat antigen test, shall be reflected in official DOH reports and tallies.
The guidelines emphasized that the collection and processing of the specimens should be done in a health facility setting, rural health units, hospitals, health facilities, and DOH-licensed clinical laboratories, to ensure that appropriate conditions are in place to minimize risk in patients and health care workers.
In areas where access to health facilities is limited, collection may be done outside of a health facility provided that a trained health care worker conducts the specimen collection in appropriate conditions are observed to minimize risk.
The DOH explained that only kits with a minimum of 80 percent sensitivity and 97 percent specificity are recommended for use and that the DOH through the Research Institute for Tropical Medicine (RITM) shall regularly publish the list of test kits that have been validated by the institute and other designated facilities. By Dexter A. See