Health Care-Associated Infections Among Neonates During the COVID-19 Pandemic.

Importance: Neonatal intensive care units (NICUs) implemented enhanced infection prevention measures during the COVID-19 pandemic to interrupt viral transmission. It was hypothesized that these measures would also reduce nonviral health care-associated infections (HAIs). Objective: To compare rates of viral and bacterial or fungal HAIs in infants admitted to the NICU before and during the pandemic. Design, Setting, and Participants: This cohort study was conducted at 12 level 3 or level 4 NICUs in the US and Canada. Participants were inborn and outborn infants admitted from March 1, 2018, to July 31, 2022, for at least 1 overnight stay at participating NICUs. Data analyses were performed from September 1, 2023, to July 28, 2025. Exposure: The viral and bacterial or fungal HAI rates during the pandemic (April 1, 2020, to July 31, 2022) were compared with those before the pandemic (March 1, 2018, to March 31, 2020). Main Outcomes and Measures: HAI incidence before and during the pandemic was expressed as episodes per 1000 patient-days and compared using pre-post and time series analysis with Poisson regression. HAI was defined as an infection diagnosed 3 or more days after admission and was confirmed using molecular diagnostics for viruses and culture of blood, cerebrospinal fluid, or urine for bacteria or fungal pathogens. Results: The full cohort comprised 48 475 infants, grouped into the viral HAI or bacterial or fungal HAI subpopulations. Among 41 889 infants with 966 025 patient-days admitted at 11 NICUs, 231 (mean [SD] gestational age, 30.5 [5.3] weeks; 147 males [63.6%]) had 241 episodes of viral HAI. Viral HAI rates decreased from 0.35 to 0.16 per 1000 patient-days with an adjusted rate ratio (aRR) of 0.45 (95% CI, 0.34-0.59). Reduced rates persisted during the later pandemic period (April 1, 2021, to July 31, 2022) compared with the corresponding period before the pandemic (aRR, 0.58; 95% CI, 0.42-0.80), even as viral infections in the community increased. Among 48 475 infants with 1 130 038 patient-days at 12 study NICUs, 1537 (mean [SD] gestational age, 29.4 [5.2] weeks; 930 males [60.5%]) had 1969 episodes of bacterial or fungal HAI. Bacterial or fungal HAI rates did not decrease from before to during the pandemic (1.70 to 1.78 per 1000 patient-days; aRR, 1.04; 95% CI, 0.95-1.14). At the site level, changes in bacterial or fungal HAI rates did not correlate with viral HAI rates. Conclusions and Relevance: This cohort study found that viral HAIs decreased significantly during the pandemic, while bacterial or fungal HAIs did not. These findings suggest that the enhanced infection prevention measures used during the pandemic may be beneficial during periods of high viral activity but offer limited additional benefit for preventing bacterial or fungal HAI.