More than half tested positive for a virus without reporting any symptoms.
Most students and staff in a Missouri school district tested positive for a respiratory virus at least once during the school year, according to findings published recently in Pediatrics.
"There is a lot to learn about respiratory viruses outside of the medical setting, and surveillance programs in the community -- specifically in schools -- can help us better understand the global impact of acute respiratory illness and respiratory virus detection," Jennifer L. Goldman, MD, MS, professor of pediatrics in the division of pediatric infectious diseases and clinical pharmacology at Children's Mercy in Kansas City, Missouri, told Healio.
The Knowledge of Infectious Diseases in Schools study included 816 participants -- 590 students (49% girls) and 226 staff (88.1% women) -- in the North Kansas City Public School District. Among the students, there were 31 pre-K students, 350 elementary schoolers, 124 middle schoolers and 85 high schoolers.
Between Oct. 31, 2022, and May 26, 2023, the researchers asked participants to submit nasal swabs once a month, as well as any time they reported at least one symptom associated with acute respiratory illness (median, seven swabs; interquartile range [IQR], six to eight). The researchers tested the nasal samples for a variety of respiratory viruses, including respiratory syncytial virus, rhinovirus/enterovirus, SARS-CoV-2 and influenza, among others.
Over the study period, 85.5% of participants had at least one virus; the median number of viruses per person was two (IQR, one to three). More than 90% of pre-K and elementary students had at least one virus, whereas 77.6% of high schoolers and 76.1% of staff tested positive for at least one virus. Among middle school students, 86.3% had at least one virus during the school year. More than half of participants (59.4%) tested positive for a virus without experiencing acute respiratory illness (ARI) symptoms, and this occurred most frequently among younger children, according to the researchers.
"The majority of participants experienced an ARI and had viral detection during the study period, but these did not always occur at the same time, highlighting the challenges of symptom screening to assess for respiratory infections," Goldman said.
The most common viruses overall were rhinovirus/enterovirus; 65.1% of participants had these viruses at least once. Other common viruses included seasonal coronaviruses (29.7%), human metapneumovirus (17.6%) and SARS-CoV-2 (15.2%). The authors reported that adenovirus was more common among younger participants (38.7% of pre-K vs. 3.5% of staff), whereas SARS-CoV-2 was more common among staff than students (26.5% vs. 10.8%).
A large portion (80.4%) of participants also reported at least one ARI during the school year (median, two; IQR, one to 29). Compared with high school students, ARIs were significantly more common among pre-K (IRR = 2.19; 95% CI, 1.52-3.15), elementary (IRR = 1.58; 95% CI, 1.23-2.03) and middle school students (IRR = 1.54; 95% CI, 1.17-2.06), as well as staff (IRR = 1.91; 95% CI, 1.51-2.43). The authors noted that the rate of ARIs among staff did not significantly differ by grade level.
"Now that we have data on respiratory viral detection in schools, we have an opportunity to learn how different infection prevention strategies in schools, including environmental modifications such as portable air cleaners and germicidal UV, may decrease respiratory viral infections and transmission," Goldman said.