Tracking the genetic diversity of SARS-CoV-2 in wastewater, rather than just viral abundance, dramatically improves the ability to monitor and predict COVID-19 outbreaks, researchers report. Their study suggests that the new approach to wastewater pathogen surveillance could serve as a powerful predictive tool for public health, providing earlier and more accurate insight into emerging waves of infection. Monitoring pathogens in wastewater has become a powerful public health tool since the COVID-19 pandemic, offering a fast, cost-efficient, and potentially less biased way to track infectious diseases across scales. Because wastewater collects biological material from an entire population, a single sample can provide a broad snapshot of community-wide infection dynamics. Yet the standard methods used to estimate disease prevalence, which rely on measuring the amount of viral genetic material recovered from a given volume of wastewater, are vulnerable to limitations. Some measurements cannot be meaningfully compared across different pathogens or settings, while others are easily distorted by environmental factors like rainfall. According to Dustin Hill and colleagues, analyzing pathogen genetic diversity through whole-genome sequencing has the potential to overcome several of the limitations of traditional wastewater surveillance methods. They argue that changes in viral genetic diversity itself may serve as a meaningful indicator of shifts in disease spread within a population.

Here, Hill et al. introduce and validate a method for estimating the prevalence of SARS-CoV-2 by analyzing the virus’s genetic diversity in wastewater. To evaluate this idea, Hill et al. retroactively applied and analyzed genetic diversity within SARS-CoV-2 from 12,290 wastewater samples collected between 2023 and 2025 from across New York state. They found that genetic diversity within a specific region of the viruses’ spike protein – the S1 NTD region – closely tracked real-world COVID-19 infection trends and, in many cases, correlated with disease activity more strongly than traditional wastewater metrics. Moreover, the authors’ statistical analyses revealed that diversity patterns in wastewater consistently preceded increases in COVID-related hospital admissions by one to two weeks, suggesting robust early warning signals of worsening disease spread. “The use of wastewater surveillance as a primary tool for monitoring population health is still a developing area,” write Justin Lessle and Ariel Christensen in a related Perspective. “Nevertheless, [this approach] has the potential to revolutionize infectious disease research and public health practice. Viral sequencing approaches such as that proposed by Hill et al. will be an important component of that success.”

The cuts to USAID (the United States Agency for International Development) in early 2025 are associated with significant increases in violent conflict in regions covering most of the African continent, a new study reports. “The obvious temptation is to read the findings … as evidence that more aid reduces conflict,” writes Axel Dreher in a related Perspective. “That would be misleading. What the authors identify is the effect of a sudden and unexpected disruption. Abrupt withdrawal removes resources, but it also interrupts contracts, staffing, procurement, and expectations. It can leave local governments, intermediaries, and citizens confronting not just scarcity but broken commitments. The effect may therefore reflect institutional disruption as much as the absence of aid itself and be much different from gradual reductions in aid.” USAID was one of the world’s largest providers of foreign assistance, operating in more than 100 countries and supporting initiatives ranging from public health, and agriculture to education, disaster relief and democratic institutions. However, less than a week after its inauguration, the second Trump administration issued sweeping cuts to USAID, marking a dramatic shift in more than 60 years of U.S. foreign policy. Emerging medical research has already linked these cuts to severe humanitarian consequences, including potentially millions of additional deaths. Yet the consequences of the sudden removal of foreign aid on political instability and different types of violence, such as armed clashes, protests and riots, or attacks on civilians, aren’t fully understood.

To address this gap, Dominic Rohner and colleagues examined the impact of USAID funding cuts on conflict across 870 subnational regions covering most of the African continent. Rohner et al. combined two detailed datasets for their analysis: the Geocoded Official Development Assistance Dataset (GODAD), which tracks foreign aid disbursements and project locations worldwide, and the Armed Conflict Location and Event Data (ACLED), which records violent events. By merging these two sources, the authors were able to link patterns of past aid distribution to subsequent patterns of violence and assess whether areas that had previously received more USAID support experienced more or different types of conflict after the aid was withdrawn. The findings show that the withdrawal of USAID is associated with significant increases in violent conflict, armed clashes, protests, and riots – particularly in regions that received substantial U.S. aid. These effects appeared immediately after USAID removal and persisted for months. What’s more, Rohner et al. found that local institutional strength further impacted these effects – weaker states experienced more pronounced increases in conflict following aid cuts, while stronger institutions more substantially mitigated the harms.

For reporters interested in topics of research integrity, Dominic Rohner notes: “Science integrity is of key importance, and now with AI it becomes cheaper to produce papers, some of which may not meet scientific standards. The role of the academic community and of leading scholarly journals is to screen between cutting-edge work and outputs of lower quality. The progress of humanity hinges on sound scientific knowledge. Widely available sound information and knowledge are not only the preconditions for government accountability but allow our economies to flourish. In economics, the leading journals have now embraced rigorous open data and replication requirements, which aims to foster scientific integrity.”

Overcoming a major hurdle in the use of microbes as medicine, researchers have introduced an implantable “living material” that contains bacteria that sense infections. It can release these therapeutic molecules on demand, while keeping them physically separated from the surrounding tissue. The findings represent a shift from passive drug depots to autonomous, responsive – and living – therapeutic systems. Engineered living cells are emerging as a new class of medicine that can autonomously sense disease and deliver treatment directly at affected sites. Unlike conventional drugs, these “living therapeutics” can sustain themselves in vivo and survive in many biological environments, including tumors, inflamed tissues, infected tissues, and even within human cells. Bacteria are particularly attractive because they can be genetically programmed to release therapeutic molecules in response to specific biological signals. However, this versatility also raises an important safety concern: therapeutic bacteria must be physically contained to prevent uncontrolled spread and potential toxicity. Previous implantable biomaterial systems, such as hydrogels and capsule-like enclosures, have shown some success in confining microbes, but only for short periods – typically no more than 2 weeks.

Tetsuhiro Harimoto and colleagues discovered that bacterial growth can be halted when the surrounding material reaches a sufficient level of stiffness, preventing the internal pressure of bacterial overgrowth from causing escape. At the same time, the material also needs to be tough enough to withstand the constant mechanical stress from surrounding tissues without cracking. To achieve this balance, Harimoto et al. created an implantable living material (ILM) consisting of a hierarchical hydrogel composed of bacteria-filled gelatin microgels embedded within a reinforced polyvinyl alcohol framework. In laboratory testing, the authors show that the material remained intact for 6 months with no detectable bacterial leakage, even under conditions designed to mimic long-term physiological stress. To evaluate the material’s clinical potential, Harimoto et al. transformed the ILM into an active therapeutic system by engineering bacteria to detect chemical signals from Pseudomonas aeruginosa, a common cause of implant-related infections. In response, the bacteria autonomously self-destructed to release an antibacterial protein that killed the pathogen. In a mouse model of joint infection, the system successfully reduced bacterial burden, demonstrating the potential of durable, programmable ILM-based therapeutics for long-term disease treatment. “Rather than treating the scaffold as a passive vehicle, Harimoto et al. treat it as an active determinant of whether contained bacteria can function safely over time,” write Kaige Chen and Quanyin Hu in a related Perspective. “This reframing brings living therapeutics closer to a model in which long-term, in vivo embedded therapeutic function replaces repeated drug administration.”

Podcast: A segment of Science's weekly podcast with Tetsuhiro Harimoto, related to this research, will be available on the Science.org podcast landing page after the embargo lifts. Reporters are free to make use of the segments for broadcast purposes and/or quote from them – with appropriate attribution (i.e., cite "Science podcast"). Please note that the file itself should not be posted to any other Web site.

A study led by a University of Louisville School of Medicine pediatrics and child neurology researcher reveals how a specific signaling mechanism in microglia, the brain immune cell, can regulate anxiety and grooming behaviors. These behaviors are core symptoms of autism and obsessive-compulsive spectrum disorders.