The Omicron variant significantly increases viral load emissions in healthcare settings: implication for healthcare...

The SARS-CoV-2 Omicron variant is transmitted via contaminated droplets and aerosols, raising concerns in healthcare settings where poor ventilation and high patient density can increase airborne viral load.

This study aimed to assess real-world exposure of healthcare workers to COVID-19-positive patients isolated in designated hospital areas, using continuous 24-h air sampling.

Air sampling was conducted inside 10 hospital rooms hosting a succession of 38 patients who tested positive for SARS-CoV-2. Sampling was performed using 37-mm cassettes placed near the patients' heads. The Omicron variant in the air was detected by RT-qPCR, with results expressed as emission rates based on air changes per hour for each room and correlated with the onset of patients' symptoms.

The SARS-CoV-2 was detected and quantified in the air of 89% of patients, indicating that 76.7% of the rooms hosting positive patients had detectable levels of airborne virus. This corresponded to an average viral emission rate of 1.45 × 10⁵ ± 2.16 × 10⁵ genomes/h per patient. Expectoration was the sole symptom significantly affecting emission rates, with patient suffering from it exhibiting values three times higher than patients without. Additionally, the room accounted for half of the variance in emission rates, suggesting that the number of patients and the room's prior usage are key determinants of viral particle exposure.

Our findings indicate that healthcare workers face significant exposure when providing care in rooms with positive patients, even when mechanically ventilated. Greater attention should be given to treating and managing these spaces to reduce the potential for viral transmission toward healthcare workers.