What Is the Incidence of Nosocomial COVID-19?

With rigorous infection control measures implemented, nosocomial COVID-19 is a rare event.

During the height of the pandemic in Boston, hundreds of patients were admitted to hospitals for COVID-19. Investigators studied patients at one Boston hospital who were diagnosed with COVID-19 on hospital day 3 or later or within 14 days after discharge to assess the risk for nosocomial acquisition of SARS-CoV-2. Measures implemented for infection control evolved over time but included screening for symptoms; testing for SARS-CoV-2; dedicated COVID-19 units with airborne isolation rooms; personal protective equipment; universal masking of staff and, later, patients; and visitor restriction.

Between March 7 and May 30, 2020, of the 9149 patients admitted, 697 (7.6%) were diagnosed with their first episode of COVID-19. Median length of stay was 7 days. Of the 697 patients, 12 (1.7%) were first diagnosed on hospital day 3 or later. The median time from admission to diagnosis was 4 days. After review of their records, the investigators classified these 12 patients as definitely community acquired (4), likely community acquired (7), or definitely hospital acquired (1). Among the 8370 patients discharged from the hospital during the study period for non-COVID conditions, 11 (0.1%) tested positive for SARS-CoV-2 within 14 days after discharge. Of these, only one case was thought to be hospital acquired.

Comment

Multiple studies have raised the alarm about nosocomial transmission of COVID-19. This study demonstrates that a well-implemented infection control program — one that includes routine testing of all admissions, serial testing of patients with clinical syndromes suspicious of COVID-19, universal masking of staff and patients, and limiting visitors — is effective in making hospital-acquired SARS-CoV-2 a rare event. For the foreseeable future, hospitals should continue to make these interventions part of their standard of care, much like universal precautions became standard of care after the emergence of HIV in the 1980s, and work with employees so that “battle-weary” staff don't let their guard down, as recently occurred at the exact same hospital where this study took place. Such incidents notwithstanding, patients need to be reassured that contracting COVID-19 is unlikely in a hospital or clinic where infection control measures are enforced.

Reviewing Author

Carlos del Rio, MD

Disclosures

Grant/Research SupportNIH/National Institute of Allergy and Infectious Diseases; NIH/National Institute on Drug Abuse

Editorial BoardsJAIDS: Journal of Acquired Immune Deficiency Syndromes; Vaccines

Leadership Positions in Professional SocietiesInternational Antiviral Society–USA (Board of Directors); Infectious Diseases Society of America (Past President)