A pilot testing project in three Omaha Public Schools buildings found COVID-19 infections that were not identified by outside testing, suggesting that infections and case rates in schools were higher than what was being reported.
The school district partnered with the University of Nebraska Medical Center and others to pilot the testing program. The program combined saliva testing intended to detect any symptom-free infections among students and staff and environmental monitoring based on testing wastewater and analyzing air and surface samples.
Infection rates detected during the five-week program were 2½ times higher for staff and nearly 6 times higher for students than what routinely was seen through absences reported to district schools for positive tests, suspected COVID-19 symptoms or high-risk exposures.
In addition, the researchers found almost 10 times the cases per capita than what was observed through community-based testing in Douglas County.
“This data shows the prevalence of (coronavirus) infection in school-aged children is being dramatically underestimated,” Dr. Jana Broadhurst, the principal investigator for UNMC’s portion of the pilot project, said in a statement.
Broadhurst said researchers now know that the majority of people infected with COVID-19 have no symptoms, and that the proportion is particularly high among children. If health officials aren’t looking for such cases, they always will undercount cases, she said.
The testing, Broadhurst said, allowed researchers to identify and send home staff and students who otherwise wouldn’t have been identified, reducing the risk of spread in the schools. Such testing also could help provide insight into how much a disease is spreading in a community where access to testing is limited.
The five-week project was conducted in November and December, a time when transmission in Nebraska was spiking. All three participating schools — Norris and Marrs Middle Schools and Bryan High School — are in the south part of the Omaha metro area, an area hard hit by the virus and where positivity rates often have exceeded those in the rest of Douglas County.
The research, which has not been reviewed by outside scientists, was published Saturday in an online forum. Other partners in the project were Nebraska Medicine, the University of Nebraska-Lincoln and OneWorld Community Health Centers.
One ongoing question during the pandemic was whether transmission is occurring within schools or whether the cases that occur there are being brought into schools by staff and students.
Broadhurst said the answer is complicated. The researchers sequenced the genomes of some positive samples. They found that the majority of those cases were not part of related transmission chains, suggesting the majority of cases were arriving from the community.
They also addressed that question through the testing of air and surface samples within the schools. The majority of samples were negative, including in cafeterias where masks temporarily are off.
But they did detect the virus in air samples in two choir rooms. One of the choir rooms also yielded a positive surface sample. Broadhurst said the environmental testing demonstrates how the testing approach may identify some activities that require modification in order to keep the environment as safe as possible.
During the pilot period, OPS was using a hybrid teaching model that staggered student attendance to decrease numbers in its buildings. About one-fourth as many students were present each day compared to a typical school year. Staff and students were required to wear masks in school buildings, where air exchange systems also had been improved.
The researchers screened asymptomatic students and staff each week with a saliva test using a streamlined version of the gold-standard PCR method. Nearly 100% of staff participated, and 12% of students signed on.
Ultimately, the researchers analyzed 2,885 saliva samples from 773 symptomless staff and students. They detected 46 positive cases, 22 in students and 24 in staff. Those figures represented a 5.8- and 2.5-fold increase in case-detection rates among students and staff, respectively, compared to outside testing mechanisms.
The cases the researchers identified were reported to the individuals, the schools and the local health department for contact tracing and isolation, just as other positive cases are reported.
The researchers also detected the coronavirus’s genetic material in wastewater samples from all three schools.
According to OPS documents filed in November, the district planned to fund the $2.3 million pilot through a combination of OPS general fund and grant money. OneWorld’s portion, nearly $80,000, also was to be covered by general fund and grant money.
Broadhurst said the researchers expanded the program to three schools in North Omaha in January through March, which will provide additional information.
“There is the intent to utilize what we have learned through the pilot to extend testing across the district,” she said.
Nationally, she said, momentum is building for school-based testing programs, with such initiatives seen as a key component of reopening schools safely.
While how testing is done may look different in every district and every state, Broadhurst said, the pilot provides a “proof of concept” that it can be done successfully in an urban district and that it can make an immediate impact on the safety of schools by quickly identifying cases.
“Our results show as many as nine in 10 student COVID-19 cases and seven in 10 staff cases might be missed by conventional reporting,” she said. “Doing this kind of testing can help lessen transmission in schools because of the ability to better isolate, trace and manage school activities.”