Widely used early warning score may help guide the urgency of antibiotic treatment for suspected sepsis

Large cohort study suggests the National Early Warning Score (NEWS2) may provide a more comprehensive framework than current guidance for determining which patients with suspected sepsis benefit from immediate antibiotics.

Harvard Pilgrim Health Care Institute

BOSTON, MA – A study of nearly 100,000 adults treated for suspected infection suggests that the National Early Warning Score (NEWS2), a score based on routinely collected vital signs that is widely used to identify patients at risk of clinical deterioration, may help clinicians identify which patients are most likely to benefit from immediate antibiotic treatment and which may safely undergo further evaluation before receiving antibiotics. NEWS2 has been adopted by many healthcare systems internationally and is recommended in the United Kingdom to help guide the urgency of antibiotic treatment in suspected sepsis, but until now there has been little empirical evidence supporting this approach.

The study, led by investigators from the Center for Sepsis Epidemiology & Prevention Studies (SEPSIS) at the Harvard Pilgrim Health Care Institute, appears in The Lancet Respiratory Medicine on August 5.

Refining Urgent Treatment Decisions in Sepsis
While timely administration of antibiotics is a cornerstone of sepsis care, diagnosing sepsis early can be complicated because its symptoms often overlap with many other serious medical conditions. Many patients treated for possible sepsis ultimately have non-infectious illnesses, exposing them to antibiotics that may offer limited benefit while increasing the risk of adverse effects and antibiotic overuse.  

Recognizing the need to balance timely treatment with diagnostic uncertainty, international sepsis guidelines have evolved from recommending immediate antibiotics for all patients with suspected sepsis toward prioritizing patients with septic shock, where the evidence suggests treatment delays have the greatest impact on survival. However, it has remained unclear whether septic shock alone is sufficient to identify all patients who may benefit from immediate antibiotics.

“The challenge with sepsis is that clinicians must decide whether to give antibiotics right away before they know with certainty whether a patient has a serious bacterial infection,” says Chanu Rhee, Harvard Medical School associate professor at the Harvard Pilgrim Health Care Institute and lead author of the study. “Our study suggests that NEWS2, a simple early warning score based on routinely measured bedside parameters, can help identify the patients most likely to benefit from immediate treatment—including many beyond those with septic shock— while allowing clinicians greater confidence to take additional time evaluating lower-risk patients."

Researchers analyzed electronic health record (EHR) data from nearly 100,000 adults treated for suspected infection in emergency departments at nine U.S. hospitals between 2015 and 2024. They examined how the relationship between antibiotic timing and survival varied according to NEWS2 scores and the presence or absence of septic shock. To the researchers' knowledge, this is the first large study to compare two international strategies for guiding the urgency of antibiotic treatment in suspected sepsis -- the United Kingdom's National Institute for Health and Care Excellence (NICE) recommendation to use NEWS2 to guide the urgency of antibiotic treatment in patients with suspected sepsis, alongside the Surviving Sepsis Campaign's emphasis on septic shock.

Key Findings

• Earlier Antibiotics Were Associated with Improved Survival in the Highest NEWS2 Category: Among patients with NEWS2 scores of 7 or higher, each additional hour to antibiotic treatment was associated with increased mortality.
• NEWS2 Identified Additional Patients Beyond Septic Shock: Many patients with NEWS2 scores of 7 or higher did not have septic shock but still showed an association between antibiotic delays and worse outcomes.
• No Survival Association at Lower NEWS2 Scores: Among patients with lower NEWS2 scores, earlier antibiotic treatment was not associated with improved survival.
• Potential to Better Guide the Urgency of Antibiotic Treatment: NEWS2 may offer a more comprehensive framework than septic shock alone for determining which patients warrant the most urgent antibiotic treatment.

"One of the most important unanswered questions in sepsis has been whether there is a better way to determine which patients are most likely to benefit from immediate antibiotics than relying on septic shock alone," said Michael Klompas, Professor of Population Medicine at Harvard Medical School and senior author of the study. "Our findings suggest that NEWS2 may provide an objective and practical way to identify those patients using a simple bedside score that is already routinely used in clinical practice."

The researchers note that the study was observational and cannot prove that earlier antibiotic treatment directly caused differences in survival. Additional studies in other healthcare settings will be important to confirm the findings.

 

About the Harvard Pilgrim Health Care Institute’s Department of Population Medicine
The Harvard Pilgrim Health Care Institute's Department of Population Medicine is a unique collaboration between Harvard Pilgrim Health Care and Harvard Medical School. Created in 1992, it is the first appointing medical school department in the United States based in a health plan. The Institute focuses on improving health care delivery and population health through innovative research and education, in partnership with health plans, delivery systems, and public health agencies. Follow us on Bluesky, X, and LinkedIn.

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Journal

The Lancet Respiratory Medicine

DOI

10.1016/S2213-2600 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

NEWS2 versus shock status to stratify antibiotic urgency in patients with suspected sepsis: a retrospective, multicentre cohort study

Article Publication Date

5-Aug-2026

 

As urban tree shade shrinks, mortality rises

New study finds that protecting mature trees could help save lives

Northwestern University

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As trees disappear from urban neighborhoods, lives may be lost with them.

In a new study, Northwestern University scientists tracked death rates and fluctuations in tree canopy cover across an 11-year period in Chicago. They found that areas experiencing greater losses in tree canopy — land covered by trees’ leafy crowns — also experienced higher mortality rates, particularly in the city’s hottest neighborhoods. 

The findings suggest cities should prioritize protecting mature trees alongside planting new ones. Given the myriad health benefits associated with trees, tree maintenance has become even more crucial as human-caused climate change drives more extreme weather and intensifies heat risks in cities.

The study will be published on Wednesday (Aug. 5) in the journal GeoHealth.

“Previous studies have mostly looked at how health outcomes are associated with static tree canopy coverage,” said Northwestern’s Daniel Horton, the study’s senior author. “These snapshot-style studies looked at mortality rates and the tree canopy at one moment in time. But cities and their tree canopies constantly change, so we looked at how the canopy and death rates change over the years. We found that as tree canopy decreases, mortality increases.”

Horton is an associate professor of Earth, environmental and planetary sciences at Northwestern’s Weinberg College of Arts and Sciences, where he leads the Climate Change Research Group (CCRG). He also is a faculty affiliate of the Paula M. Trienens Institute for Sustainability and Energy and the Roberta Buffett Institute for Global Affairs.

Exploring nature-based solutions

The study grew out of the Buffett Institute’s Defusing Disasters Working Group, an interdisciplinary initiative that unites climate scientists, physicians, public health experts, city leaders and community partners to explore how extreme weather affects vulnerable populations in Chicago. Co-led by Horton, the group also develops practical strategies to help cities reduce health risks and strengthen climate resilience.

“The Defusing Disasters Working Group set out to determine what makes Chicago residents vulnerable to extreme heat,” Horton said. “We found that a number of different factors contribute to heat vulnerability, and trees are one part of the equation.”

A walking tour of Chicago’s North Lawndale and Douglas Park areas inspired Harrison Garcia, the study’s lead author and a medical student at Northwestern University Feinberg School of Medicine, to consider canopy coverage.

“I noticed how much more exhausting it felt to walk through areas with little tree cover compared to nearby blocks lined with mature trees,” said Garcia, who also is a member of the Defusing Disasters Working Group. “I remember thinking that if the heat was affecting me so noticeably during a short walking tour, it must be shaping people’s health over the long term.”

To capture canopy changes, the team analyzed annual satellite measurements of tree canopy across every Chicago census tract from 2011 through 2021. Then, they combined satellite data with more than 220,000 death records from the Illinois and Chicago Departments of Public Health.

To isolate the relationship between tree canopy and mortality, the researchers developed a statistical model that accounted for differences in summer temperatures, air pollution, income, population size, racial/ethnic residential segregation and other neighborhood-level factors that can influence health. This approach enabled the research team to distinguish the effects of changing tree canopy from differences that already existed among neighborhoods.

Not all neighborhoods are affected equally

The team found that a neighborhood’s overall tree canopy within each year was not significantly associated with mortality. Instead, what mattered were the year-to-year changes in tree canopy. Increases in canopy were consistently associated with fewer deaths from cardiovascular disease, respiratory disease, several musculoskeletal conditions and mental health-related illnesses.

“We used a technique called K-means clustering to group Chicago neighborhoods based on three factors: tree canopy, temperature and mortality,” said study co-author Benjamin Barrett, a Ph.D. candidate in health and biomedical informatics at Feinberg and member of the Defusing Disasters Working Group. “That allowed us to identify patterns across Chicago and to pinpoint where protecting and expanding tree canopy is needed most.”

The geographic disparities were striking. According to the model, neighborhoods on the South and West sides tended to experience hotter summer temperatures, greater absolute canopy losses and higher mortality than other parts of the city. Neighborhoods along Lake Michigan generally experienced cooler temperatures and lower mortality, while areas near the Forest Preserves had the city’s largest tree canopy and experienced relatively lower mortality.

Mature trees matter

The study coauthors underscore an often-overlooked point: Planting trees and increasing tree canopy are not the same. While young saplings take years to develop broad, leafy crowns, mature trees already provide extensive shade and cooling. Losing those trees — to disease, storms or development — can erase decades of canopy growth almost overnight.

“Chicago must both maintain the canopy it has and expand the canopy where it’s needed most,” said study coauthor Raed Mansour, a member of the Defusing Disasters Working Group and of the Openlands Board of Directors. “That means protecting mature trees from unnecessary removal, providing ongoing care for existing trees, replacing removed trees and investing in their long-term survival.”

To illustrate the potential benefits, the research team modeled what might happen if Chicago increased tree canopy by about 0.03% each year, which is roughly equivalent to planting 14,000 trees annually. The model estimated this increase was associated with roughly 105 fewer deaths annually.

Trees as public health infrastructure

While trees can cool neighborhoods by providing shade and reducing the effects of urban heat islands, they also have numerous other health benefits. Trees improve air quality, encourage outdoor activity and contribute to healthier neighborhoods.

“Trees provide dozens of benefits,” Mansour said. “They decrease stress, anxiety and blood pressure and increase social cohesion. They also reduce soil erosion and support biodiversity. Maintaining the urban canopy and planting trees where they are needed are both important. Many folks see trees primarily as aesthetics features or amenities, but they should be recognized as part of our public health infrastructure.”

The study, “Increasing urban tree canopy associated with reduced mortality: a longitudinal analysis of Chicago neighborhoods,” was supported by the Buffett Institute for Global Affairs.

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Journal

GeoHealth

DOI

10.1029/2025GH001651 

Article Title

Increasing urban tree canopy associated with reduced mortality: a longitudinal analysis of Chicago neighborhoods

Article Publication Date

5-Aug-2026

 

No clear evidence that common embryo transfer techniques improve IVF success

Preparation techniques used before embryo transfer, considered the most critical step in the IVF process, show no proven effect on pregnancy rates and remain inconclusive due to limited or low-quality data, a new Cochrane review finds.

Cochrane

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Preparation techniques used before embryo transfer, considered the most critical step in the IVF process, show no proven effect on pregnancy rates and remain inconclusive due to limited or low-quality data, a new Cochrane review finds.

Embryo transfer is the final and most vulnerable stage in in vitro fertilization (IVF) with only a third of transfers resulting in pregnancy. To improve the odds, clinicians use various techniques, but it’s uncertain which techniques result in higher pregnancy rates. 

Practice varies across clinics. Some centres routinely use preparatory techniques such as adjusting bladder fullness, while others do not consider them necessary and omit them entirely.
The researchers analyzed 11 studies involving a total of 2,524 women undergoing embryo transfer. They examined three categories of preparation techniques used by fertility clinics: straightening the utero-cervical angle by having women arrive with a full bladder, removing cervical mucus before transfer, and "afterloading," a technique for guiding the embryo through the cervix.

Overall, the researchers found that none of the three techniques was backed by reliable evidence of benefit. The included trials were small and were riddled with methodological weaknesses, meaning the evidence was rated low or very low certainty, and the authors did not find grounds to recommend any of these practices over standard care.

“To an extent, this is a case of tradition driving practice rather than the evidence,” says Dr Ryosuke Akino, practicing obstetrician-gynaecologist from Kato Ladies Clinic. “Current practices in this area often reflect local protocols, clinician preference, and historical convention rather than strong, high-quality evidence.”

Little data was available on side effects, but the review team – comprising methodologists and practising obstetrician-gynaecologists – noted that full bladder preparation and cervical mucus removal are generally considered safe, with no clear evidence of harm or major complications.

"While these techniques are generally considered safe, it’s still important to test their effectiveness," says Dr James Brown, obstetrician-gynaecologist from Women’s Health and Research Institute Australia. 

Dr Akino and Dr Brown add: "A full bladder can be uncomfortable, although it may ease catheter insertion in certain uterine positions and reduce procedural difficulty. Mucus removal is usually quick, but if done roughly and causes bleeding, it may affect the woman’s experience. Overall, the risks are minor and relate mostly to discomfort and procedural factors rather than clinical harm."

While most aspects of IVF have advanced considerably over the past few decades, this particular step has remained largely unchanged. Research attention has instead shifted toward embryo quality and genetic factors, which have a greater bearing on success rates than transfer technique. Embryo transfer is also highly dependent on the person doing the procedure and hard to standardize, making large, rigorous trials difficult to design. Women are often reluctant to risk valuable embryos in a randomized trial. 

“Sixteen years of research still haven’t answered a basic IVF technique question,” says Dr Noyuri Yamaji from Showa Medical University, Japan. “This is a critical step in the IVF process and these small changes and techniques have the possibility to make a massive difference, but we won’t know more until more robust, better-quality trials are conducted.” 

All the studies included were conducted in high-income countries, meaning the findings may not generalize to other healthcare settings and populations. Because these procedures are inexpensive and simple to change, the authors argue it may be especially valuable to prioritize research in resource-limited settings, where basic procedural standardization could matter more than advanced technical modifications.
 

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Journal

Cochrane Database of Systematic Reviews

DOI

10.1002/14651858.CD007682.pub3 

Method of Research

Systematic review

Subject of Research

People

Article Title

Techniques for preparation prior to embryo transfer

Article Publication Date

5-Aug-2026

Zoo-housed lions show wild-style behaviors when fed whole carcasses

Adelaide University

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A new Australian study has found that feeding zoo-housed lions whole animal carcasses on a feast-and-fast schedule encourages behaviours more closely aligned with those seen in the wild.

Published in Applied Animal Behaviour Science, the research from Adelaide University and Monarto Safari Park in South Australia examined how African lions responded when animal care staff introduced whole animal carcasses every nine days, building on an existing feast-and-fast feeding routine for a group of adult males.

Using around-the-clock video monitoring over three months, researchers found the lions spent significantly longer feeding, rested more after meals, and displayed activity patterns that mirrored the natural cycles of wild lions.

Lead author Lesia Hryhorenko from Adelaide University's School of Animal and Veterinary Sciences said the study offers new insights into how feeding schedules influence the behaviour of carnivores in human care.

“Wild lions don't eat at the same time every day. They experience natural periods of feasting and fasting depending on hunting success,” Hryhorenko said.

“We wanted to understand how African lions in human care respond when feeding routines more closely resemble those natural patterns.”

The research team – which included visiting Belgium Masters student Florence Demoulin from the University of Liege – monitored three adult male lions at Monarto Safari Park before and after the introduction of whole-carcass feeding.

During the experimental phase, zookeepers fed the three adult male lions with approximately 200 kilograms of carcasses, which remained available for up to three days, followed by a period of rest and digestion.

Eight infrared cameras recorded the lions' behaviour continuously, creating one of the most detailed 24-hour datasets yet collected on African lions in human care under a carcass feeding regime.

The study found that feeding activity increased dramatically on carcass days, with lions spending almost three times longer feeding than they normally would. Feeding bouts were also more frequent and lasted longer as the animals tore, manipulated and consumed the carcasses, exhibiting a wider range of natural feeding behaviours.

After feeding, the lions spent much more time lying down and resting. As the fasting period progressed, movement gradually increased again, creating a behavioural rhythm that closely resembled the feast-and-fast cycles observed in wild lion populations.

“Providing whole carcasses changes much more than the nutritional content of the diet,” Hryhorenko said.

“It gives lions the opportunity to engage in behaviours such as tearing, pulling and manipulating food over extended periods, which are important components of their natural feeding ecology.”

Researchers also examined pacing, a repetitive behaviour often associated with anticipation in carnivores in human care.

While pacing increased slightly over the course of the study, it did not steadily rise during fasting periods. Instead, peaks occurred around routine keeper arrival and habitat-shifting times, suggesting the behaviour was linked more closely to predictable feeding routines than hunger.

The researchers observed no increase in aggression or social instability around carcass feeding events.

Co-author Associate Professor Alexandra Whittaker said the study highlights the value of long-term, continuous monitoring when assessing animal behaviour and management practices.

“Many zoo studies focus only on what happens immediately after food is provided,” Associate Professor Whittaker said.

“Our results show that feeding schedules can influence behaviour for days afterwards, making it essential to look at behavioural patterns across the entire feeding cycle rather than a single feeding event.”

The researchers say future studies combining behavioural observations with physiological measures could help further evaluate how different feeding regimes affect animal welfare and wellbeing.

‘Effects of implementing a whole-carcass feeding routine on the behaviour of zoo-housed African lions’ is published in Applied Animal Behaviour Science. DOI: 10.1016/j.applanim.2026.107041

Notes for media

Footage of African lions at Monarto Zoo can accessed via this link

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Journal

Applied Animal Behaviour Science

DOI

10.1016/j.applanim.2026.107041 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Effects of implementing a whole-carcass feeding routine on the behaviour of zoo-housed African lions

Article Publication Date

1-Aug-2026

Were there tiny dinosaurs? New study explores one of evolution’s biggest mysteries

Mathematical models reveal that even the smallest dinosaurs were surprisingly large—and suggest that flight allowed birds to break the rules

American Museum of Natural History

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image: 

A model of Microraptor being put on display at the American Museum of Natural History. Microraptor was one of the smallest known dinosaurs, weighing about one pound—roughly the size of a large rabbit.

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Credit: Alvaro Keding / ©AMNH

Dinosaurs are famous for being big, from the towering Tyrannosaurus rex to the colossal Apatosaurus. But a new study published today in the journal Evolution by scientists at the American Museum of Natural History and Princeton University suggests that one of the greatest mysteries of dinosaur evolution isn’t how some species became giants—it’s why even the smallest dinosaurs never became truly tiny.

Using mathematical models to investigate the evolution of body size across vertebrates, researchers found that while energetics and physiology can explain the sizes of mammals, birds, and turtles, they cannot explain why the smallest non-bird dinosaurs remained unusually large throughout their evolutionary history. Instead, the findings suggest that competition with small-bodied early mammals may have prevented dinosaurs from becoming mouse- or sparrow-sized animals that are so common among vertebrates today.

“Everyone loves a giant dinosaur,” said study co-author Roger Benson, the Macaulay Curator of Dinosaur Paleobiology at the Museum. “But we decided to look at the other end of the scale. The absence of tiny dinosaurs may be just as interesting as the existence of giant ones. We already knew that dinosaurs prevented mammals from evolving to large sizes before the end-Cretaceous mass extinction. Here we suggest that mammals in turn prevented dinosaurs from evolving to small sizes.”

While the largest dinosaurs weighed more than 80 tons, the smallest known non-bird dinosaurs weighed nearly one pound (approximately 450 grams)—about the size of a large rabbit. This is more than 200 times larger than the world’s smallest bird, the bee hummingbird, which weighs just 1.75 grams and the smallest mammal, the Etruscan shrew, which is about 1.8 grams. The smallest lizard, the dwarf gecko, is only 0.15 grams.

Roughly 75 percent of living mammal species and 90 percent of living bird species are smaller than the smallest non-bird dinosaurs.

“Small animals dominate modern ecosystems,” said Stephanie Lechki, the lead author of the study and a postdoctoral fellow at Princeton University. “If we want to understand how today’s biodiversity evolved, we need to understand why tiny dinosaurs appear to have been missing.”

One possible explanation is simply that scientists haven’t found fossils of the smallest dinosaurs. Tiny animals are harder to discover, and their delicate bones are less likely to fossilize. But Benson and Lechki argue that explanation is unlikely because fossil deposits that preserve dinosaurs routinely preserve much smaller animals as well, including mammals, lizards, amphibians, and other vertebrates. If mouse-sized dinosaurs had existed, scientists would expect at least some of them to appear alongside these other small animals.

Instead, the fossil record suggests that genuinely tiny non-avian dinosaurs were rare, or maybe they were absent altogether.

To investigate why, the researchers used mathematical models that predict how natural selection shapes body size, based on the physiology of energy uptake and reproduction. These models are based on the idea that animals should evolve into sizes that help them most efficiently turn energy into offspring.

This approach successfully predicted observed body size distributions of mammals, birds, and turtles, but it did not work for snakes, lizards, and crocodilians. And even after accounting for a wide range of physiological possibilities, the models could not explain why most non-avian dinosaurs were so much larger than expected.

The findings suggest that physiology alone cannot explain dinosaur body sizes. Instead, ecological factors—including competition, predation, and the availability of different ecological niches—likely played a large role in limiting how small non-avian dinosaurs could become.

The study also offers new insight into one of the most dramatic transitions in vertebrate evolution: the emergence of birds. Although birds evolved from dinosaurs, modern birds are dramatically smaller than even the smallest known non-avian dinosaurs. Birds evolved body sizes far smaller than any other group of dinosaurs in just a short time after they first appeared in the Early Cretaceous.

The researchers found that this shift toward miniature body sizes also cannot be explained by physiology alone. Instead, they propose that the evolution of powered flight fundamentally changed the ecological opportunities available to early birds. By taking to the air, birds may have escaped the ecological constraints that prevented their dinosaur ancestors from evolving into much smaller animals.

“The ability to fly may have opened entirely new ways of life,” Lechki said. “Once birds entered those new ecological niches, they were free to evolve body sizes that had simply not been possible for other dinosaurs.”

Future studies may reveal even more about the ecological pressures that determined which body sizes flourished and which never evolved at all.

“We have this unusual situation where the ancestors of dinosaurs could be tiny. The living descendants of dinosaurs—birds—they can be tiny. But dinosaurs themselves seemed to be forbidden from being tiny,” Benson said. “And we don’t really understand that yet, but it’s a question we should continue to explore if we really want to understand dinosaurs and their fascinating biology.” 

Study DOI: 10.1093/evolut/qpag117

 

ABOUT THE AMERICAN MUSEUM OF NATURAL HISTORY (AMNH)

The American Museum of Natural History in New York City, founded in 1869 with a dual mission of scientific research and science education, is one of the world’s preeminent scientific, educational, and cultural institutions. The Museum encompasses more than 40 permanent exhibition halls, galleries for temporary exhibitions, the Rose Center for Earth and Space including the Hayden Planetarium, and the Richard Gilder Center for Science, Education, and Innovation. The Museum’s scientists draw on a world-class permanent collection of more than 30 million specimens and objects, some of which are billions of years old, and on one of the largest natural history libraries in the world. Through its Richard Gilder Graduate School, the Museum offers two of the only free-standing, degree-granting programs of their kind at any U.S. museum: the Ph.D. program in Comparative Biology and the Master of Arts in Teaching (MAT) Earth Science residency program. Visit amnh.org for more information.

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Journal

Evolution

DOI

10.1093/evolut/qpag117 

A fossil of Microraptor, one of the smallest known dinosaurs. 

Credit

Mick Ellison / ©AMNH