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Surveillance pool testing for COVID-19 offers new way to catch outbreaks quickly

A whiteboard in the office of principal Helenann Civian at South Boston Catholic Academy tracked pool testing being done at the school.
A whiteboard in the office of principal Helenann Civian at South Boston Catholic Academy tracked pool testing being done at the school.Suzanne Kreiter/Globe staff

A new approach to COVID-19 testing could revolutionize our ability to return more quickly — and safely — to workplaces and classrooms, and kick-start the economy before the vaccine is fully distributed.

Several laboratories in the region are working with a handful of schools and other organizations to employ this new approach, known as surveillance pool testing. The strategy involves frequent, wide-scale testing of everyone in an office, business, or school to detect cases early and fast.

So far, the state has relied on diagnostic testing — a more traditional, singular test strategy — and urged only those people with symptoms or possible exposure to get swabbed. The Massachusetts testing system, cited as among the best in the nation, remains patchy and pushed to the limit, and is struggling to provide the amount of testing needed.

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Epidemiologists and other public health experts have long said that surveillance pool testing is the best path forward, but there hasn’t been the infrastructure or political effort to make such an ambitious endeavor possible. Things are changing now.

With the anticipated launch of surveillance pool testing in public schools across the state, expect to hear more soon about this approach. Until then, here are some basics.

What is pool testing?

Pooling is a testing technique where samples from multiple people are bundled together and processed by a lab. This makes testing faster and less expensive. For example, swabs from all the students in a kindergarten classroom can be collected in one vial and and tested as one sample. If a pool tests positive, each member of the pool is tested again to locate the source of the infection. Pool testing works best when there is a low prevalence of cases, experts say.

A better question: What is surveillance testing?

While pooling is a means to make testing faster and more cost effective, surveillance testing is a strategy that involves frequent, repeated sampling (weekly or more often) of everyone in an organization or group. It enables workers or students to meet in person because the frequent testing detects cases before they cause massive spread. The key is to return results rapidly and test on a consistent basis.

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Colleges and universities in Boston used this strategy to reopen their campuses this fall. The experiment was largely successful, and positivity rates on the campuses remained much lower than in the city at large. Many businesses and other organizations now view the colleges as a model they hope to replicate.

The colleges’ effort worked in large part thanks to the Broad Institute, the genomics research center in Cambridge that quickly transformed itself into a large-scale COVID-19 testing facility with capacity to quickly process the massive number of samples coming each day. The Broad is now developing pooling technology in a partnership with CIC Health.

How is it different from the testing we already have in the state?

Until now, testing in Massachusetts has been diagnostic, designated for people with symptoms or exposure to the virus. Surveillance testing, however, tests everyone, regardless of symptoms or known exposure, and its strength is in catching asymptomatic cases or catching cases before symptoms appear.

Earlier this month the Baker administration announced that it would begin to use this type of testing to reopen more secondary school classrooms this semester. Several districts had already begun on their own.

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Epidemiologists and other experts since the beginning of the pandemic have advocated for this approach, saying it could help reopen the economy before a vaccine is fully distributed.

“The idea of pool testing is where we should be and where we should have been a while ago,” said Dr. Robyn Riseberg, founder of Boston Community Pediatrics, a nonprofit, pediatric private practice involved in one pool testing pilot.

“The only way to keep [workers] safe, keep the economy open, is to have testing. We know it is the key and so having this relatively available pool testing that just becomes a part of your weekly life is so critical,” she said.

How does it work?

Surveillance testing can be done several ways. Ginkgo Bioworks, a biotech company in the Seaport District, has developed a swab system where students wipe the inside of their nostrils, then place the swab in a container with other samples that is shipped to a lab. If a pool tests positive, the school or business must re-test each member individually to find the positive person or people. Ginkgo’s goal is to bring the cost down to $5 to $7 per individual test. Colleges this fall paid $25 per individual test. The cost of an individual diagnostic test is around $80 to $100.

Several early childhood education centers in the region have taken part in a saliva-based test pilot run by the advocacy organization Neighborhood Villages. Staff spit into a tube at home then it is mailed to Mirimus lab in New York. In this system, members of a pool that tests positive do not have to be re-tested because lab workers can disaggregate the samples in the pool to find the positive person or people.

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“For us it has been invaluable,” said Lauren Cook, the chief executive of Ellis early learning center in the South End, one of eight organizations participating in the pilot program. “It provides such a sense of security.”

Cook said the testing has caught a positive case most weeks, and the person was quickly isolated so the virus didn’t spread to anyone else.

Who provides this type of testing?

At the moment, three main labs offer pool testing for businesses and schools in the region. Ginkgo Bioworks is expanding its pool testing pilot program for schools in Massachusetts and across the country. Mirimus, in Brooklyn, N.Y., provides saliva-based pool testing, and recently opened a second lab in Las Vegas.

Jason Kelly, the chief executive of Ginkgo Bioworks, believes this type of testing will be useful in future pandemics, and for achieving more immediate goals, like President Biden’s promise to open most schools during his first 100 days in office.

“If we want to have an alternative tool [besides lockdowns] it has to be looking for people that don’t have symptoms and letting them know,” he said.


Laura Krantz can be reached at laura.krantz@globe.com. Follow her on Twitter @laurakrantz.