As respiratory viruses surge, new research underscores how masking and testing policies in hospitals directly influence infection rates, shaping future strategies for patient and staff safety.

Study: Testing and Masking Policies and Hospital Onset Respiratory Viral Infections. Image Credit: Ground Picture / Shuttersstock.com

In a recent study published in JAMA Network Open, researchers investigate how changes in hospital policies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and masking have influenced the rate of nosocomial or hospital-acquired respiratory viral infections.

The impact of masking and testing on hospital-acquired infections

Respiratory viral infections caused by pathogens like influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 pose significant risks in healthcare settings, especially for vulnerable hospitalized patients. During the coronavirus disease 2019 (COVID-19) pandemic, masking, and routine viral testing were adopted worldwide to limit both within-community and in-hospital transmission of SARS-CoV-2.

Several studies have demonstrated that these measures effectively reduced hospital-acquired infections, minimizing complications and patient mortality. However, as COVID-19 vaccination rates increased and public health emergencies subsided, many institutions ceased these precautions. Emerging research suggests that lifting these measures may lead to higher nosocomial infection rates, especially when viral activity in the community is high.

Despite these concerns, few studies have systematically quantified the consequences of discontinuing testing and masking or examined the potential benefits of reinstating targeted interventions. Understanding the relationship between policy changes and infection rates is critical for developing strategies to safeguard hospitalized patients and healthcare staff during periods of heightened respiratory viral transmission.

About the study

The current study’s researchers investigated the impact of changes in hospital protocols for SARS-CoV-2 testing and masking on the rate of hospital-acquired respiratory infections. To this end, a cohort analysis across 10 hospitals within the Massachusetts General Brigham system was performed between November 2020 and March 2024. The 10 hospitals included tertiary, community, and specialty care settings.

Four policy phases were investigated: universal masking and testing before the Omicron period, universal masking and testing when the Omicron variant was in circulation, cessation of these masking and testing measures, and reinstatement of masking for healthcare workers.

Nosocomial infections were defined as positive polymerase chain reaction (PCR) results occurring over four days after admission. Comparatively, community-acquired infections reflected those that were identified within the first four days.

Data were collected on testing compliance and frequency, with adherence measured based on the number of admissions with polymerase chain reaction (PCR) testing. Statistical analyses included a Poisson interrupted time-series model to estimate changes in infection rates while adjusting for community infection trends and seasonality.

Additionally, a review of 100 randomly selected hospital-acquired SARS-CoV-2 cases after the cessation of universal testing was conducted to verify classification accuracy while assessing symptom onset, exposure history, and PCR cycle thresholds.

The study’s overarching aim was to isolate the effects of testing and masking policies while addressing limitations such as possible misclassification and variable policy compliance. All findings were adjusted to exclude biases from seasonal variations or changes in community infection rates.

Study findings

Discontinuing universal masking and SARS-CoV-2 testing was associated with a significant rise in hospital-acquired respiratory viral infections, whereas reinstating masking for healthcare workers significantly reduced these infections.

During the period of universal masking and testing, hospital-onset infections accounted for 2.9% of the weekly ratio to community-onset cases. This ratio increased to 15.5% after these measures ended and subsequently decreased to 8% following the reintroduction of healthcare worker masking.

Specifically, a 25% rise in hospital-acquired infections was observed after masking and testing measures were discontinued. Thereafter, a 33% reduction was observed after healthcare workers resumed masking.

Of hospital-onset SARS-CoV-2 cases analyzed after the masking and testing policies were discontinued, 89% exhibited new respiratory symptoms, 80% were associated with PCR cycle thresholds under 30, and 27% of cases had known exposures to SARS-CoV-2. These findings confirm the importance of masking and testing during periods of increased community transmission.

Although SARS-CoV-2 cases dominated early in the study, influenza and RSV cases rose following the removal of universal measures. This transition aligned with changes in testing frequency, which were significantly reduced from 92.9% to 26.5% of admissions after the cessation of routine testing.

Conclusions

COVID-19 masking and testing policies significantly influenced the rates of nosocomial respiratory viral infections. Furthermore, reintroducing masking for healthcare workers effectively reduced nosocomial infections, particularly during periods of heightened community transmission.

These findings demonstrate the value of adaptive infection control strategies in healthcare settings to balance resource use with patient safety. Thus, policymakers should consider targeted interventions like masking for healthcare workers to mitigate risks during respiratory viral surges.