MANILA — Several doctors associations on Tuesday said they do not recommend the use of rapid antibody tests for COVID-19 to screen employees returning to work.
“The sensitivity or the yield of a positive test (of an antibody test) is very low (at) about 20%. And among that 20%, 2/3 will be false positive," said Dr. Issa Alejandria of the Philippine Society of Microbiology and Infectious Diseases (PSMID) during a virtual briefing with media on Tuesday noon.
"Mataas ang false positive (There is a high possibility of false positive).”
Alejandria said this is based on previous studies.
“These tests do not detect the virus, (but) just the antibodies produced,” explained Philippine College of Occupational Medicine (PCOM) President Dr. Phil Pangilinan, who also does not recommend rapid tests as a screening tool.
Unlike the polymerase chain reaction (PCR) based tests preferred by the World Health Organization (WHO) and the Department of Health (DOH), rapid antibody tests require blood samples instead of nose and throat swab samples.
Alejandria explained that the rapid antibody tests, which some business leaders are hoping to use for mass screening of employees, can only detect two types of antibodies — when you already have an infection, and when you have recovered from an infection.
The DOH had already warned the public that antibody tests are unable to detect the first few days of a virus since the body has yet to produce antibodies to fight it. Alejandria said people who also recovered from other coronaviruses may test positive using the rapid test kits.
During the virtual briefing, the doctors discussed how having many false positive cases would be detrimental to the Philippines.
Alejandria said that a person who gets a false positive “will be unnecessarily isolated.” This can result in wastage of personal protective equipment and human resources as workers are deployed to tend to and to trace contacts of a person who isn’t even really infected with COVID-19.
“After this, healthcare workers are forced to do contact tracing at a time where they are already undermanned at the frontline. Once contact tracing is completed, those who came into contact with the worker are then required to get quarantined unnecessarily,” the Philippine Medical Association (PMA), the Philippine College of Physicians (PCP), the Philippine Society of Microbiology and Infectious Diseases (PSMID), the Philippine College of Occupational Medicine (PCOM), the Philippine Society of Public Health Physicians (PSPHP), the Philippine Society of General Internal Medicine (PSGIM), and the Philippine Academy of Family Physicians (PAFP) said in a joint statement.
On the other hand, she said a false positive for antibodies that appear upon recovering from COVID-19 would result in “false security” since the patient would think that he or she is already immune.
Dr. Rogelio Dazo of the Philippine Medical Association (PMA) also pointed out that the Research Institute for Tropical Medicine has yet to validate any antibody test kit and that it might take 2 to 4 weeks before the process is completed.
Action for Economic Reforms’ (AER) Dr. Eddie Dorotan, who is a former mayor of Irosin, Sorsogon, said requiring businesses to pay for such tests will only make things unnecessarily harder for owners.
“As a screening test sa mga manggagawa, sayang ang pera natin at magkakaroon tayo ng false expectation at dangerous,” he said, echoing the other doctors’ concerns.
(As a screening test for workers, it’s a waste of money and we’ll have false expectations, which can be dangerous.)
“Aside from the debilitating effects to the health of Filipinos, COVID-19 has also devastated many businesses, which were forced to close down during the enhanced community quarantine. These companies will only suffer further if they are required to pay for these unreliable and potentially harmful tests,” the doctors said in the joint statement.
The doctors agreed that the most cost-effective and efficient way to prepare employees to go back to work is through the government’s minimum health standards, which includes physical distancing, proper hygiene, cough etiquette and the wearing of face masks.
Because it is hard to accurately detect asymptomatic carriers of COVID-19, the doctors advised the public to be very careful and to assess their own condition through a 14-day test.
Dr. Noel Espallardo, board member of the Philippine Academy of Family Physicians (PAFP), explained that the 14-day test is a series of questions asked to learn the patient’s history of travel, exposure and respiratory symptoms.
“If all the questions are 'no', then the probability that the patient or the client has COVID is very low…Fit to work (certificate) can be given,” he said.
Dr. Aileen Espina, Technical Committee Representative of the Philippine Society of Public Health Physicians (PSPHP), said that while they respect the choice of business and industry leaders, they also need to carefully plan how the testing should be done.
“The company should ensure that the necessary prevention and control measures are institutionalized,” she said, raising concerns of the need for an infectious waste disposal plan.
Espina explained that the insistence of some to use rapid antibody tests, despite accuracy concerns, might be because of the psychological effects of the pandemic.
“I think it’s the fear, it’s the anxiety on the part of the employers and the part of the employees,” she said.
“Unless we are able to address the source of the anxiety of all the people that are engaged here, hindi natin mahahanapan ng solusyon (we won’t be able to find a solution).”
And without a vaccine against COVID-19, the doctors said that the best intervention would still be physical distancing and other minimum health standards.