Is Routine COVID-19 Saliva Testing in Childcare an Effective Prevention Measure?

It may seem odd to ask parents to send their child to daycare with a vial of saliva, but from a community health perspective, routine saliva testing is a noninvasive, cost-effective method for monitoring COVID-19 cases among young children, according to research presented at the National Association of Pediatric Nurse Practitioners (NAPNAP) National Conference on Pediatric Health Care held March 15 to 18, 2023, in Orlando, Florida.

Weekly screening for COVID-19 using at-home saliva was feasible and may mitigate outbreaks, said study author Hibah Mahwish Askari, MS, from Yale School of Nursing, New Haven, CT.

The study, which was funded by Yale and the National Institutes of Health, included 142 children and 125 childcare employees across 8 childcare centers. In total, 3509 saliva samples were collected from children (aged 6 months to 7 years) and staff enrolled in 8 childcare facilities starting in October 2020. Data presented in this study was collected through May 2022, however, the saliva collection program is ongoing.

Saliva samples were analyzed using PCR testing with the goal being to detect infections early prior to transmissibility, explained Askari. Another goal of the study was to determine if weekly testing would be sufficient to mitigate spread, especially in asymptomatic and presymptomatic participants.

“By allowing for early detection, transmission can be mitigated, allowing child care centers to remain open,” Askari said in an interview. “Especially during a wave or rise of community infections, this kind of sensitive asymptomatic testing is of course favorable to no testing at all.”

As in other studies on this topic performed on college campuses, another goal was to balance testing frequency, sensitivity, and cost, Aksari said. “Besides the saliva testing, serology data was collected to determine whether infections were being missed by weekly PCR testing but that could be detected based on seroconversion.” 

Guidance on At-Home Saliva Sample Collection

Saliva collected was used in this study because of the relative aversion to nasal swabs among young children. Given the challenges associated with collecting saliva samples from young children at home, researchers developed 2 sets of guidance for parents based on their child’s age (<3 or ≥3 years).

The saliva collection process varied for each child, explained Askari. “Some younger children were able to collect the saliva without the bulb pipette and similarly occasionally an older child would need extra assistance. The first few weekly collections for each child were done with a member of the study team to allow parents to have a resource available to assist in finding the best method to make saliva collection an easy process each week. Because of this, we were able to assist parents in identifying if their child required a pipette or could be encouraged to provide the sample independently,” Askari explained.

Askari and colleagues provided these age-appropriate instructions to parents via video chat. For most children younger than 3 years, parents were instructed to collect the saliva sample immediately before feeding their baby; for toddlers, parents were advised to provide the child with a chew toy to prevent them from biting down on the pipette. Parents were instructed to collect saliva from under the tongue of a child sitting upright or along the cheeks if the child was on their side and to repeat the collection process until they had collected between 0.5 and 1 mL of saliva.

For most children older than 3 years, parents were instructed to place the child’s favorite food in front of them or tell the child to think about their favorite food so that saliva would pool under the child’s tongue. After about 30 seconds, the parents were instructed to place the collection tube along the child’s lower lip and tell the child to spit into the tube, repeating as necessary until the child spit between 0.5 and 1 mL of saliva into the tube.

Demographics on disabilities among the children were not collected, but additional support, via video call, was provided to parents and staff upon request, Askari said.

Researchers instructed participating childcare employees to immediately place the saliva samples in designated coolers as soon as the child arrived at the childcare center. Half of the health centers had samples picked up on Wednesdays and the other half on Fridays, with the timing based on study feasibility and laboratory testing volumes.

The saliva samples were transported to a partnering clinical laboratory or RT-PCR using Yale-developed SalivaDirect testing and results were sent to parents via a patient portal within 24 hours. To ensure consistent weekly participation, parents received an email reminder on the evening saliva samples were due to be collected and dropped off at the childcare center the next morning.

Study Outcomes

Most of the saliva samples were negative for SARS-CoV-2 (n=3387) and 18 tests were positive. Nine tests were inconclusive. Of the 95 tests that were considered invalid, 61 had a leak in the collection tube, 26 had an insufficient quantity of saliva, and 8 had a PCR failure.

Askari and colleagues conclude that saliva testing in childcare centers is feasible and provides important access to testing in an often overlooked population.

A Look to the Future

We asked Askari what the future of this ongoing program will be as COVID-19 is no longer perceived as an acute and immediate threat. She answered: 

“This study was designed as a community-based participatory research (CBPR) project, which means that it involves community members as stakeholders. Engagement is largely dependent on the needs of the community and centers – if they don’t perceive the need, then the community chooses to stop.

Now, testing has been a challenge and there has been a drop off recently in testing numbers, however, with recent RSV outbreaks and the rise of other respiratory pathogens with the return to childcare after initial closures, there is a clear need for this kind of testing program incorporating other respiratory pathogens as well. In addition to SARS-CoV-2, the team has received approval to test the performance of saliva testing for other respiratory pathogens as well in a research context. It is the hope that if this multiplexed testing platform performs well, then approval for Clinical Laboratory Improvement Amendments (CLIA)-level testing for multiple pathogens could be envisioned —all from a single saliva sample!

Testing practices will continue to depend on public perceptions, new knowledge gained from research, public health communications, new variants, and the changes we will likely see in transmission going forward.”

Visit Clinical Advisor’s meetings section for more coverage of NAPNAP 2023.

Reference

Rayack EJ, Askari HM, Zirinsky E, et al. Routine saliva testing for SARS-CoV-2 in children: methods for partnering with community childcare centers. Presented at: NAPNAP National Conference; March 15-18, 2023; Orlando, FL.