Rapid antibody tests best used on recovering COVID-19 patients, repatriated OFWs: DOH

Kristine Sabillo, ABS-CBN News

Posted at Apr 23 2020 03:50 PM | Updated as of Apr 23 2020 06:08 PM

MANILA — Because it measures antibodies and not the genetic sequence of the COVID-19 virus itself, rapid test kits are best used to check the condition of recovered patients and repatriated overseas Filipinos, the Department of Health said Thursday.

The clarification came as some local government units are considering using rapid antibody test kits for their constituents.

While Polymerase Chain Reaction (PCR) test kits are still considered the gold standard of the DOH, the government allowed the use of rapid test kits, which requires blood instead of swab samples, because of the country’s limited PCR test kits and testing capacity amid the COVID-19 outbreak.

However, positive results using the rapid test kits still require validation via PCR testing since it can be prone to false negatives or false positive.

RECOVERED PATIENTS

“Pwede nang gamitin (ang rapid test kits) 'pag ang isang pasyente ay idi-discharge,” Health Undersecretary Maria Rosario Vergeire said during a video conference with media on Thursday morning.

(This can be used when the patient is about to be discharged.)

The health official explained that COVID-19 rapid test kits can detect two types of antibodies: Immunoglobulin G (IgG) and Immunoglobulin M (IgM). IgM is a sign of early infection, while IgG is a sign of recovery.

In an interview with DZMM on Wednesday afternoon, Vergeire said that asymptomatic patients who test positive for IgG can already be discharged from the hospital.

“(Kung) IgG positive, maaari na natin silang palabasin. Pero wag nating itatali ang ating pasyente na porke walang rapid antibody test na nagawa ay hindi natin pauuwiin kahit walang sintomas,” Vergeire said.

(If IgG positive, they can already be released. But let’s not delay the release of the patient if there is no rapid antibody test, especially if he does not have symptoms anymore.)

The health official reiterated that their guidelines allow patients to return home if they no longer have symptoms, and other tests such as X-rays show recovery. The only requirement is for the patient to undergo another 14-day home quarantine and self-isolation.

OVERSEAS FILIPINOS

Vergeire, during the DZMM interview, said another good use for the rapid test kits are for initial screening of overseas Filipino workers returning home.

“Pinayagan na ng IATF na magamit ang rapid antibody test (sa OFWs). Pagdating nila dito sa atin sa Pilipinas, ite-test sila para magkaroon ng baseline sa kanila habang tayo ay magsasagawa ng quarantine sa kanila,” Vergeire said.

(The IATF already approved the use of rapid antibody tests (for OFWs). When they arrive here in the Philippines, we test them so we have a baseline while they undergo quarantine.)

Vergeire said the repatriates will then be tested after 14 days to ensure that they are free from the disease when they return to their families.

COMMUNITY TESTING

The health official told DZMM that rapid test kits can also be used in communities if there is a shortage in PCR kits. But there are guidelines to be followed.

“Unang-una, ang rapid antibody test, hindi yan ginagamit for us to diagnose COVID. Hindi n'ya masasabi sa'yo kung ikaw ay positive o negatibo,” she said.

(First of all, rapid antibody tests cannot be used to diagnose COVID. It cannot tell you if you are positive or negative.)

What it can measure are the antibodies in an individual who is sick.

“Kailangan, hindi nya (LGUs) ito i-consider as a standalone test. Ibig sabihin, kahit ginagawa nila yan sa kanilang lugar, kailangan may validation ng RT-PCR,” she added.

(LGUs should not consider it as a standalone test. This means, even if they use it in their area, there should be validation using RT-PCR tests.)

Vergeire has explained that because rapid antibody test kits can have false negative or false positive results, it can be dangerous to the public.

She said that a person with a false negative result can be sent home and unwittingly infect his family and neighbors, while a person with a false positive result can be brought to a quarantine facility where he will end up being infected by other people there.

Vergeire said this is why rapid test kits should always be handled by health workers, and its results explained by a doctor.