Editorial: Why a Day 1 swab is wrong

We continue to point out true science amid a political tussle at the risk of sounding like a voice in the wilderness. We have said a couple of times, since the clash in national and local protocols for inbound Filipinos in our international ports caught the limelight, that the basic but most crucial difference lies in the required swab timing that one can hardly be called “innovation” at all.

President Rodrigo Duterte felt the weight in the Department of Health’s recommendation that the Inter-Agency Task Force (IATF) for the Management of Emerging Infectious Diseases stand by its protocol for inbound Filipinos—which is a 14-day quarantine, the first 10 days in a facility and the remaining four in their places of destination provided they turn out negative after the seventh-day swab test. Thus, the President’s order to reopen the Mactan-Cebu International Airport after ensuring that the IATF protocol is enforced.

The Provincial Government’s version requires a swab upon arrival. We’d like to point out the perils of this protocol. While we appreciate the preemptive test modality that the Province wants to set in place and its point in not making the lives of returning Filipinos any more difficult amidst the pandemic, an RT-PCR swab upon arrival and the consequent three-day isolation still leave our borders porous to the potential entry of the virus, specifically the variants that have plagued not a few countries. The IATF Resolution 114 stated it clearly in two of its whereases that our health agencies’ biosurveillance have detected the variants that were found in India and in 26 other countries. This was short of saying the Philippines’ port of entries have been pervious as far as its supposed screening protocols were concerned. Thus, Resolution 114.

One of the earliest lessons that health experts learned in this pandemic is that early tests have proven to be less accurate. This is a fact that is true not only in the case of Covid-19, and any medical practitioner knows that viruses need a certain period of incubation before they are pervasive enough to figure in one’s body. While the timeline differs in every person, scientists found that in the case of Covid-19, it would take at least seven days for the virus to reach detectable level.

The Massacusetts Institue of Technology, for instance, found a hundred percent probability of false-negatives in tests taken during the four days following a person’s exposure to the virus. It becomes 67 percent on the fourth day. The results, of course, differ according to the sensitivity of the particular test being used. The ACP journal also published under the Annals of Internal Medicine a study entitled: “Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction-Based Sars-CoV-2 Tests by Time Since Exposure” concludes that: “Over the four days of infection before the typical time of symptom onset (Day 5), the probability of a false-negative result in an infected person decreases from 100 percent on Day 1 to 67 percent on Day 4.”

These findings have been corroborated by the rest of the medical community and, therefore, had become standard knowledge that guided quarantine policies in many countries, the Philippines included. This is where the IATF’s protocol comes from.

To release a repatriated overseas Filipino worker or returning overseas Filipino on the third day of quarantine following a negative result from a Day 1 swab, therefore, opens the possibility of open transmission. These individuals will be travelling to their final places of destination and fat chance they will be exposing themselves to other people. And what if they carry the more potent variants?

The saddest of scenarios is that these issues have been muddled by non-experts jumping into the fray, arguing on non-sequiturs and wayward conclusions—on legalities and politics—as if the virus cares who wins in elections.