Mitigating lockdowns: Can pooled testing help?

Published August 3, 2021, 12:22 AM

by Raymundo W. Lo, MD, FPSP

Raymundo W. Lo, MD

So, we’re headed for another two-week lockdown due to the Delta variant surge threat. But lockdowns per se will only bring temporary relief, as we’ve seen in the past year. The same goes for different countries seeing surge after surge.

While vaccination is the key to ending the epidemic — and yes, all vaccines work to prevent severe disease, hospitalization, and death — we need to make sure we prevent further spread while awaiting herd immunity. One way we can do it is by intensifying our test-and-trace efforts. While it is true that testing can be expensive, the price of the alternative is exorbitant hospitalizations and a ruined economy runs into the billions. We need to put out the small fires which if not tamped down, will lead to huge conflagrations.

The Philippine Society of Pathologists Inc. (PSPI), the national association of pathologists who head the COVID-19 testing laboratories in the country, has proposed and concept-proved RT-PCR pooled testing as a means of making testing more affordable and as efficient as single testing in many scenarios. This has been approved by the DOH, and many COVID-19 labs are now certified to perform it. We have proven the concept to work with our pilot projects all over the country, and we are using it in many non-clinical (asymptomatic) situations, such as the (testing of domestic tourists and returning OFWs, workplace testing, and surveillance testing).

Pooled testing is a method of RT-PCR testing that involves putting part of the swab samples of five persons into one tube and testing that tube as one sample. If it tests negative, all  five samples are released as negative. If it tests positive, each of the five samples is tested separately, and the results of the individual tests are released. During the surge four months ago, we again urged the use of pooled testing in localized outbreaks to prevent further spread in specific areas where there were many cases.

Our strategy aims to mitigate the adverse effects of more extensive lockdowns by limiting them to specific locales, such as a barangay reporting 10 or more cases in one day. The scheme will entail instantly isolating the positive cases, and testing their immediate contacts individually. Those found negative will undergo a five-day quarantine with the rest of the barangay. Then all will undergo pooled testing. All who test negative can then be released, except the close contacts of the positive cases. Hence, for most of the barangay residents, the lockdown would last only a week instead of two. They can then engage in work sooner than in a two-week lockdown.

Shortening the lockdown by even just a week will translate to billions of pesos in government savings. Jobs would be saved, thus relieving the government the burden of providing aid for hundreds of thousands unable to work under lockdown. With pooled testing and isolation, there would be no need for lockdowns of entire towns and cities nor the attendant costs of government aid, which it can’t afford anyway.

Pooled testing can also help LGUs focus their test-and-trace efforts on certain areas rather than dissipate their energies on a whole town or city. Barangay workers of unaffected areas can assist their fellow workers in lockdown sites to do contact tracing and enforce community health standards.

This strategy was presented to the National Task Force for Pandemic Response and was well received. However, no further action was taken. We had proposed doing a pilot project with LGUs, but this was at the time when everyone was gearing up for vaccination drives, so there were no takers.

Funding may be an issue, but it is significantly cheaper than the alternative scenarios. Pooled testing can save as much as 72 percent of costs. In areas where the positivity rate is less than 3 percent, the price is only P750;  at 10 percent, it’s P1,500. Even tests done individually can be at P2,200, which is certainly a lot less than the mandated rate of P3,800 per test.

More importantly, pooled testing increases our capacity by five times more,  without additional investments in infrastructure, equipment, test kits, and personnel. Increased testing rates correlate with better government management of the pandemic, as shown in other countries. China was able to open up its economy even before vaccination started by aggressively pool testing entire cities of millions in two weeks. Other countries have likewise used pooled testing to open up their economies earlier.

The WHO has set a benchmark of under 10 percent positivity as adequate testing. If the rate is more than 10 percent, we are not testing enough, and clearly, our rates are going even higher as we speak. We are currently testing less than one percent of our population on a daily basis. Moreover, my colleagues and I have learned of instances where those who test positive were merely confined to their homes by barangay authorities, but the rest of the family were not tested. At the end of two weeks, they were all allowed to leave home.  But those close contacts might have caught the virus late in the quarantine period and would spread it unwittingly in the community, since they were not tested.

Identifying the infected persons, isolating them, and tracing their contacts are really the key to limiting the COVID-19 spread. With pooled testing, we can do it less expensively, more efficiently, and in the appropriate time frame.

We now have over 50 laboratories that can do pooled testing, yet their capabilities are underutilized. All we ask for is to pilot this concept. It will certainly help a long way in lessening the burdens of the pandemic, especially on our poor countrymen. The PSPI is ready to partner with local government units in performing this service for our people. Will there be any takers this time?

(The author is an American board-certified pathologist and a fellow of the Philippine Society of Pathologists Inc. He spearheaded the pooled testing concept and is the principal author of the research paper on pooled testing in the Philippines, which was the basis for its approval for use by the DOH.)