Interventions such as testing patients for COVID-19 on admission, isolation of ill healthcare workers (HCWs), and universal HCW masking from March 2020 to July 2022 significantly reduced SARS-CoV-2 transmission among patients and staff in UK hospitals, suggests a simulation study led by UK Health Security Agency researchers in London.
The findings were published last week in BMC Infectious Diseases.
The scientists used an individual-based model of in-hospital SARS-CoV-2 spread and a panel of infection-prevention experts to estimate the effectiveness of disease-mitigation measures during the first 2 years of the COVID-19 pandemic. The study period spanned the predominance of different viral variants and the availability of different vaccines and doses.
"Model parameters and associated uncertainty were derived using national and local data, literature review and formal elicitation of expert opinion," the study authors wrote. "We simulated scenarios to explore how many nosocomial [hospital-related] infections might have been seen in patients and HCWs if interventions had not been implemented."
Several potential confounding factors
Results of the simulation suggest that, without COVID-19 testing at hospital admission, other infection-prevention protocols, and limits on occupancy and visitors, twice as many patients could have been infected in the first 2 years of the pandemic.
"Testing and cohorting of patients and isolation of HCWs were the most important interventions for reducing transmission to patients and HCWs preventing up to 34% (30–40%) of infections," the researchers wrote. "We also identified a significant role for masking, with universal masking being more impactful than masking around patients alone (40% (30–52%) vs 17% (14–20%) reduction)."
They cautioned, however, that their study focused on the overall impact of masking but didn't distinguish between the use of respirators or surgical masks. Also, it assumed total compliance with measures such as testing and isolation and didn't consider individual HCW differences in risk of infection when outside the hospital.
Importance of high levels of compliance
The infection-prevention measures had the greatest effect during times of limited immunity (beginning of the pandemic and during the Omicron variant surge) and were least effective during times of high immunity from COVID-19 vaccination and previous infection.
These results highlight the importance of maintaining high levels of compliance to infection prevention and control measures in hospitals and have important implications as hospitals prepare for a surge in demand due to emerging winter pressures and COVID-19.
"Model findings suggest that collectively the interventions introduced over the SARS-CoV-2 pandemic in England averted 400,000 (240,000 – 500,000) infections in inpatients and 410,000 (370,000 – 450,000) HCW infections," the researchers wrote.
The authors said that the findings point to a role for limited patient visitation during times of high community prevalence.
"These results highlight the importance of maintaining high levels of compliance to infection prevention and control measures in hospitals and have important implications as hospitals prepare for a surge in demand due to emerging winter pressures and COVID-19," they concluded.
