Research Recap: June 20 – July 1

Research Recap: June 20 – July 1

July 21, 2022

A biweekly overview of recent studies published by Institute investigators and their collaborators spans a wide variety of topics, including:

Incidence of hospital-acquired Omicron infections versus prior COVID-19 variants; Survey of hospital infection control practices after the Omicron surge; Association of street-view greenspace exposure and objective sleep characteristics among children; Timing of cow's milk protein introduction and childhood adverse reactions.

For all faculty publications, see our Publications page. For up-to-date media coverage and research findings, visit In the Media, and follow us on Twitter. To search for a subject matter expert, visit our Investigator Directory.

stock photoHospital-based study shows that the increase in hospital-acquired COVID cases mirror increases in community case numbers during the Omicron surge

The SARS-CoV-2 Omicron variant is more contagious than prior variants, leading to large increases in community cases. However, little is known about the incidence of hospital-acquired Omicron infections versus prior variants. A team of researchers led by Michael Klompas, with Meghan Baker and senior author Chanu Rhee, conducted a retrospective hospital-based study to examine all nosocomial infections during the Omicron surge vs an earlier wave when wild-type variants predominated. Infection control policies were similar across periods and included universal masking, daily employee health attestations, testing on admission and 72 hours after admission, visitor restrictions, contact tracing, and free on-demand testing for employees. Results, published in JAMA, reported an increase in hospital-onset infections during the Omicron wave, which mirrored similar increases in community and health care worker case numbers. Authors note that the increase in hospital-onset infections associated with the Omicron variant despite consistent infection control policies and mandated employee vaccinations underscores the risk of nosocomial transmission, especially when community incidence rates are high, and the need for enhanced infection control strategies.

Institute Investigator(s): Meghan Baker, Michael Klompas, Chanu Rhee


Survey of U.S. hospitals reveals variation in infection control policies following the Omicron surge

The COVID-19 pandemic highlighted the critical importance of rigorous infection control practices in preventing viral transmission in healthcare settings. Recommendations from the CDC have continued to evolve in response to real-world experiences on the effectiveness of infection control strategies, but CDC guidance is not prescriptive and allows institutions considerable discretion for key practices. A team of investigators led by Chanu Rhee and including Meghan Baker and senior author Michael Klompas, surveyed hospital epidemiologists from leading U.S. medical centers to understand infection control practices following the wave caused by the SARS-CoV-2 omicron variant in order to compare infection control practices across institutions. Findings, published in Infection Control and Hospital Epidemiology, report that while N95 masking and universal patient testing were uniformly reported (across 91% of responding institutions), other COVID-19 infection control practices vary substantially. Authors suggest that clearer public health guidance and transparency around hospital policies may facilitate more consistent national standards.

Institute Investigator(s): Meghan Baker, Michael Klompas, Chanu Rhee


Examining the association of greenspace exposure and sleep among children

stock photoGreenspace may benefit sleep by enhancing physical activity or reducing stress and/or air pollution exposure. Studies on greenspace and children's sleep are limited, and most use satellite-derived measures that do not capture ground-level exposures that may be important for sleep. A team of investigators including Emily Oken and senior author Peter James examined associations of street view imagery (SVI)-based greenspace with sleep in Project Viva using deep learning algorithms to derive novel metrics of greenspace. Findings, published in Environmental Research, report that these novel metrics of greenspace exposure based on SVI at mid-childhood were not associated with objectively measured sleep duration or efficiency in early adolescence, but did observe an association between percentage of grass at mid-childhood and more sleep fragmentation in early adolescence. Authors suggest that SVI metrics may have the potential to identify specific features of greenspace that affect sleep.

Institute Investigator(s): Peter James, Emily Oken

Timing of cow's milk protein introduction and childhood adverse reactions

Current guidelines emphasize early introduction to potentially allergenic foods, but the optimal timing, amount, and exposure routes for foods other than peanuts are not well-established. Cow's milk is often the first allergenic food introduced through infant formulas. A team of investigators led by Karen Switkowski and including Emily Oken and Joanne Sordillo examined timing of cow's milk protein introduction in relation to reported cow's milk adverse reactions throughout childhood among children in the Project Viva cohort. Findings, published in Journal of Allergy and Clinical Immunology: In Practice, report that an early window for promoting tolerance of cow’s milk protein may exist immediately after birth if exposure is sustained. Another optimal exposure window from 2 weeks to 6 months may exist for those not given formula immediately after birth. Based on these findings, authors suggest that parents who intend to breastfeed exclusively and avoid cow’s milk-based formula supplements consider whether an infant was given supplemental formula after birth when deciding timing of introducing cow’s milk protein to the diet.


Institute Investigator(s): Emily Oken, Joanne Sordillo, Karen Switkowski