Young Children Found to Carry the Most viruses during flu and cold season, Study Reveals

A new study published in the journal of Pediatrics found that pre-kindergarten and elementary school children had the highest rates of virus detection and acute respiratory illnesses (ARIs) when compared to older students and staff, confirming that younger students harbor the most germs during flu and cold season.

Schools are well-known spots for infectious disease transmission, yet, detailed data on how often respiratory viruses spread among students and staff have been limited. The Knowledge of Infectious Diseases in Schools (School KIDS) study was conducted in a large Kansas City public school district with over 20,000 students to fill that gap.

From November 2022 to May 2023, a total of 816 participants (590 students and 226 staff members) took part in the study. The participants self-collected nasal swabs and reported respiratory symptoms weekly. This research received 5,981 specimens and 5,198 symptom surveys, which allows for an in-depth look at how respiratory viruses circulate across different grade levels.

The study found that 85.5% of participants had at least one virus detected, while 80.4% reported at least one episode of acute respiratory illness during the study period. When adjusted for school attendance days, the rates revealed that the youngest children had the highest levels of infection.

Pre-kindergarten and elementary school students showed the greatest virus detection rates, with 1.46 and 1.51 cases per 100 enrollment days, respectively. These groups were followed by middle school students (1.19), high school students (0.90), and staff members (0.87).

However, when looking at the rates of actual illness episodes the results were slightly different. Pre-kindergarten students and school staff had the highest ARI rates, at 1.66 and 1.45 per 100 enrollment days, respectively. Elementary and middle school students followed closely, while high school students showed the lowest rate at 0.76.

This research suggest that younger children’s developing immune systems and close-contact classroom environments may contribute to higher transmission rates. For staff, frequent exposure to multiple classrooms and age groups could explain their elevated illness rates.Overall, these findings suggest that younger students face the highest risk of respiratory virus infections, while both pre-K children and staff experience the most frequent illness episodes which highlights the need for improved prevention measures in early education environments.

Source:

Goldman, J. L., Lee, B. R., Almendares, O. M., Kirking, H. L., Derado, G., Banerjee, D., Sasidharan, A., Porter, J., Tilsworth, S., Selvarangan, R., & Schuster, J. E. (2025). Respiratory virus detection and acute respiratory illness rates in students and staff in schools. Pediatrics, 156(4). https://doi.org/10.1542/peds.2025-070886