Nosocomial Transmission Dynamics of SARS-CoV-2

Nosocomial transmission of SARS-CoV-2 refers to infections acquired within healthcare facilities, encompassing both patient-to-patient spread and transmission between patients and healthcare workers. During the pandemic, hospitals have served as critical nodes for viral amplification, where factors such as ward design, bed occupancy, ventilation and cohorting of COVID-19 and non-COVID-19 patients have influenced outbreak dynamics. Single-room availability, airflow volume per bed and rapid identification of index cases have emerged as key determinants of in-hospital transmission risk. Understanding these dynamics is essential not only to protect vulnerable patients and staff but also to mitigate spill-over into the wider community via discharged patients and asymptomatic carriers. Comprehensive surveillance integrating epidemiological data, real-time diagnostic testing and viral genomic sequencing has shed light on the relative importance of different transmission pathways. Studies have demonstrated that patient-to-patient transmission often exceeds that driven by healthcare workers, while super-spreading events can propel abrupt surges of hospital-onset infections. As variants with increased transmissibility continue to arise, adaptive infection control measures—ranging from enhanced ventilation and physical distancing to more frequent screening and cohort isolation—are critical for interrupting chains of transmission within healthcare settings.

Research from Nature Portfolio

Large-scale analysis of hospital admissions in England has revealed that between 95,000 and 167,000 inpatients acquired SARS-CoV-2 in acute settings during the period from June 2020 to March 2021. Crucially, patients infected within the hospital constituted the primary source of onward transmission to fellow inpatients. This work also identified structural risk factors such as low proportion of single rooms and reduced heated volume per bed, suggesting that targeted improvements in ward infrastructure could substantially lower nosocomial incidence and amplify the effectiveness of community-level interventions. A complementary study combining viral genomic and epidemiological data across two pandemic waves within a large UK NHS trust has quantified shifts in transmission routes over time. During the first wave, staff-to-staff transmission accounted for nearly a third of in-hospital spread, whereas by the second wave patient-to-patient transmission rose above 50 per cent of events. The analysis further showed that hospital-acquired cases had a high propensity for onward transmission compared with community-acquired cases, underscoring the need for rapid case detection, routine lateral flow testing and enhanced ward-level isolation to break chains of nosocomial infection.

Nosocomial Transmission Dynamics of SARS-CoV-2 publication trend

The graph below shows the total number of articles in nosocomial transmission dynamics of sars-cov-2 across all publications each year (not limited to Nature Index journals).

Technical terms

Nosocomial transmission: Infection acquired by a patient or healthcare worker within a healthcare facility rather than in the community.

Polymerase chain reaction (PCR): A molecular technique used to amplify and detect specific genetic sequences of SARS-CoV-2 for diagnosis.

Viral genomic sequencing: Determination of the SARS-CoV-2 RNA sequence to track transmission chains and detect variants.

Super-spreading event: An incident in which an infected individual transmits the virus to a disproportionately large number of secondary cases.

Aerosol-generating procedure: A medical intervention that produces airborne particles capable of carrying infectious virus, such as intubation.

References

1. The burden and dynamics of hospital-acquired SARS-CoV-2 in England. Nature (2023).
2. Characterising within-hospital SARS-CoV-2 transmission events using epidemiological and viral genomic data across two pandemic waves. Nature Communications (2022).
3. A new method for near real-time, nationwide surveillance of nosocomial COVID-19 in Norway: providing data at all levels of the healthcare system, March 2020 to March 2022. Eurosurveillance (2023).
4. Multiple pathways of SARS-CoV-2 nosocomial transmission uncovered by integrated genomic and epidemiological analyses during the second wave of the COVID-19 pandemic in the UK. Frontiers in Cellular and Infection Microbiology (2023).
5. Transmission of community- and hospital-acquired SARS-CoV-2 in hospital settings in the UK: A cohort study. PLOS Medicine (2021).
6. Superspreaders drive the largest outbreaks of hospital onset COVID-19 infections. eLife (2021).