New York City's practice of randomly testing students attending school in-person has left out dozens of children at Park Slope school, raising questions about the effectiveness of a system that is designed to keep students and teachers safe in a pandemic.

Ever since the randomized testing program for COVID-19 launched two months ago, P.S. 107 John W. Kimball elementary school has never tested the students in one of two cohorts of in-person learners, according to teachers and data verified by Gothamist/WNYC. And it's likely the cohort of students missing out on the program will go untested for the remainder of 2020.

The lack of participation calls into question the school's COVID-19 positivity rate, which is currently 0%, and undercuts Mayor Bill de Blasio's promise he made to parents and teachers that testing would be rigorous throughout the year.

The practice was confirmed in an internal newsletter by the school's principal Eve Litwack. In the newsletter, which was obtained by Gothamist, Litwack "expressed our concern to our Superintendent and the people in charge of the testing that only one cohort has ever been tested."

Litwack added, "I've been told that this should be rectified in the new year, especially as weekly testing becomes more routine."

The principal also revealed that testers are typically there for just one hour or so, offering little time for teachers who are not part of the randomized pool to be tested, a condition worked out between the city and the United Federation of Teachers union.

City officials began the randomized testing program in October following the reopening of schools for in-person learning on September 29th for young students. It started as a monthly program until the entire school system shifted completely to remote learning on November 18th, after the city's seven-day average positivity rate for COVID-19 hit 3%. When schools reopened on December 7th, de Blasio leaned even harder on testing, increasing it from monthly to weekly. The city contracted with BioReference Labs and Fulgent Labs, Inc., to carry out the nose swab testing.

P.S. 107 has two cohorts—Cohort A and Cohort B—created to minimize the number of students inside the school per day while adhering to de Blasio's desire for in-person learning. (Public school students from first through fifth grade must be tested, with exemptions made to 3K to kindergarten students.) Each open school is required to test 20% of in-person students and faculty, and, at P.S. 107, this translates to 35 students and 15 adults.

Cohort A comes in every Tuesday, Thursday, and every other Monday. A review of the Department of Education's website that tracks the number of students and staffers tested shows only Cohort A underwent testing: October 27th with 57 students tested; November 17th with 107; and December 8th and December 14th with 27 students each. No students or staffers tested positive.

Jennifer Tirado, an in-person teacher who arrives at the school five days a week, noticed the pattern of the same students getting tested when lab technicians with BioReference Labs kept arriving on the same day as when students in Cohort A were in the classroom.

"They have never come to test on a Cohort B day, so that already skews the data, because you're only testing the same people. To then only test...the same people over and over again doesn't make any sense," Tirado said. "It just goes along with all the other lines that we've been fed about the safety in the schools, or their lack of a plan for what's going to happen here."

During the December 8th visit, Tirado, who has been repeatedly chosen for the randomized testing, said technicians only stayed for one hour to administer tests, leaving some of the teachers who had requested to be tested in the lurch.

"They had to make it to two other schools within the time of the day, and the day ends at two o'clock. So they had to leave. And really, we were told that all teachers can be tested," Tirado said.

In an interview with Gothamist/WNYC, Dr. Irwin Redlener, an epidemiologist at Columbia University, recommends that all cohorts in a school be included in the random testing. This practice of testing both cohorts is not explicitly detailed on the DOE website, which simply states that 20% of a school population will be tested. In some instances, the webpage outlining the program still mentions that the program is monthly instead of weekly.

Nathaniel Styer, a spokesperson for the DOE, said in a statement that it's now working with the school “on changing the day of the week testing occurs to increase variance in population."

"With random selection, it is entirely appropriate for some of the same students or staff to be tested multiple times as a part determining the rate of COVID-19 in a community," Styer said. "And we also make an effort to regularly vary both the days and cohorts that are being tested.”

Styer confirmed that different cohorts at a school are supposed to be tested weekly. The practice, doesn't appear to have happened at P.S. 107.

"Generally, the sense in the school is that the teachers want to be there and want to teach the kids but we want the DOE and the United Federation of Teachers to do what they've said what they promised to do so that everybody remains safe," Tirado said. "It's the right thing to do."