Climate change is a global process that affects human health in a variety of complex ways. Wildfires, heat waves, hurricanes, floods, and other climate-related weather events can result in illness, injury, and death. Indirect health threats are cause for concern, too. For example, changes in temperature and rainfall can affect the lifecycle of mosquitoes that transmit diseases such as malaria and dengue fever, thereby paving the way for new outbreaks.
Environmental disruptions worsened by climate change can reduce air quality, diminish water resources, and increase exposure to higher temperatures and pathogens. As a result, we see greater health risks in susceptible individuals such as children, the elderly, the poor, and people with underlying conditions, both in America and around the world.
For decades, the National Institute of Environmental Health Sciences and other NIH institutes and centers (ICs) have advanced important research into how climate change affects health. But expanding knowledge in this area and addressing other key challenges will require much more collaboration. The time is now for an all-hands-on-deck scientific effort—across NIH and the wider biomedical research community—that spans many interconnected disciplines and fields of inquiry.
That is why I am excited to join forces with several other IC directors to launch the NIH Climate Change and Health Initiative. By working together, NIH institutes and centers can harness their technologies, innovative research approaches, and talent to advance the science of climate change and health. Through this timely effort, we will promote resilience in vulnerable communities because our research will help them to understand, prepare for, and recover from climate-related health challenges.
Our Strategic Framework outlines why it is important to go beyond studying the health effects of climate change. We must involve impacted communities in solutions-focused research that empowers them, health care practitioners, and health and social services agencies to reduce climate-related health risks. By generating scientific evidence for public health action, we can use a health equity approach to boost climate resiliency among at-risk groups, whether in the U.S. or low- and middle-income countries.
At the heart of the initiative is a push for transdisciplinary, team-based science that boosts training, research capacity, and community engagement. Our immediate goals are to use existing grant programs to strengthen research infrastructure and enhance communication, internally and externally.
Also, with dedicated support from several ICs and the Office of the Director (OD), NIH is funding a research coordinating center and a community engagement program. The coordinating center will help NIH scientists collaborate and manage data. And the community engagement program will empower underserved populations by encouraging two-way dialogue in which both scientists and community members learn from each other. That inclusive approach will improve research and mitigation efforts and reduce health disparities.
In addition, several Notices of Special Interest are now open for applications. The NIH invites scientists to submit research proposals outlining how they plan either to study the health effects of climate change or develop new technologies to mitigate those effects. Also, with OD support, a Climate and Health Scholars Program will launch later this year. Scientists working on important research will share their expertise and methodologies with the NIH community, spurring opportunities for further collaboration.
Going forward, any additional support from the White House, Congress, and the public will allow NIH to further expand the initiative. For example, we urgently need to test novel interventions for reducing heat stress among agricultural workers and to scale up early-warning systems for climate-related weather events. There is also opportunity to use laboratory-based and clinical methodologies to expand knowledge of how climate factors, such as heat and humidity, affect key cellular systems, including mitochondrial function.
To fill those and other research gaps, we must draw on an array of skill sets and fields of inquiry. Therefore, our Strategic Framework outlines the importance of supporting adaptation research, basic and mechanistic studies, behavioral and social sciences research, data integration, disaster research response, dissemination and implementation science, epidemiology and predictive modeling, exposure and risk assessment, and systems science. Tapping into those areas will help us tackle climate-related health challenges and develop effective solutions.
In recent years, in-depth reports and assessments have provided conclusive evidence that climate change is significantly altering our environment and impacting human health. Although the science of climate change and health has progressed, much work remains. We hope that the Climate Change and Health Initiative expands scientific partnerships and capacity throughout NIH and across the global biomedical and environmental health sciences communities. Greater collaboration will spur new knowledge, interventions, and technologies that help humanity manage the health effects of climate change and strengthen health equity.
(Note: The Initiative’s Executive Committee includes the following IC directors: Richard Woychik, National Institute of Environmental Health Sciences [chair]; Diana Bianchi, Eunice Kennedy Shriver National Institute of Child Health and Human Development; Gary Gibbons, National Heart, Lung, and Blood Institute; Roger Glass, Fogarty International Center; Joshua Gordon, National Institute of Mental Health; Eliseo Pérez-Stable, National Institute on Minority Health and Health Disparities; and Shannon Zenk, National Institute of Nursing Research.)
Note: Dr. Lawrence Tabak, who performs the duties of the NIH Director, has asked the heads of NIH’s Institutes and Centers (ICs) to contribute occasional guest posts to the blog to highlight some of the interesting science that they support and conduct. This is the 14th in the series of NIH IC guest posts that will run until a new permanent NIH director is in place.
With the start of summer coming soon, many are hopeful that the warmer weather will slow the spread of SARS-CoV-2, the novel coronavirus that causes COVID-19. There have been hints from lab experiments that increased temperature and humidity may reduce the viability of SARS-CoV-2. Meanwhile, other coronaviruses that cause less severe diseases, such as the common cold, do spread more slowly among people during the summer.
We’ll obviously have to wait a few months to get the data. But for now, many researchers have their doubts that the COVID-19 pandemic will enter a needed summertime lull. Among them are some experts on infectious disease transmission and climate modeling, who ran a series of sophisticated computer simulations of how the virus will likely spread over the coming months . This research team found that humans’ current lack of immunity to SARS-CoV-2—not the weather—will likely be a primary factor driving the continued, rapid spread of the novel coronavirus this summer and into the fall.
These sobering predictions, published recently in the journal Science, come from studies led by Rachel Baker and Bryan Grenfell at Princeton Environmental Institute, Princeton, NJ. The Grenfell lab has long studied the dynamics of infectious illnesses, including seasonal influenza and respiratory syncytial virus (RSV). Last year, they published one of the first studies to look at how our warming climate might influence those dynamics in the coming years .
Those earlier studies focused on well-known human infectious diseases. Less clear is how seasonal variations in the weather might modulate the spread of a new virus that the vast majority of people and their immune systems have yet to encounter.
In the new study, the researchers developed a mathematical model to simulate how seasonal changes in temperature might influence the trajectory of COVID-19 in cities around the world. Of course, because the virus emerged on the scene only recently, we don’t know very much about how it will respond to warming conditions. So, the researchers ran three different scenarios based on what’s known about the role of climate in the spread of other viruses, including two coronaviruses, called OC43 and HKU1, that are known to cause common colds in people.
In all three scenarios, their models showed that climate only would become an important seasonal factor in controlling COVID-19 once a large proportion of people within a given community are immune or resistant to infection. In fact, the team found that, even if one assumes that SARS-CoV-2 is as sensitive to climate as other seasonal viruses, summer heat still would not be enough of a mitigator right now to slow its initial, rapid spread through the human population. That’s also clear from the rapid spread of COVID-19 that’s currently occurring in Brazil, Ecuador, and some other tropical nations.
Over the longer term, as more people develop immunity, the researchers suggest that COVID-19 may likely fall into a seasonal pattern similar to those seen with diseases caused by other coronaviruses. Long before then, NIH is working intensively with partners from all sectors to make sure that safe, effective treatments and vaccines will be available to help prevent the tragic, heavy loss of life that we’re seeing now.
Of course, climate is just one key factor to consider in evaluating the course of this disease. And, there is a glimmer of hope in one of the group’s models. The researchers incorporated the effects of control measures, such as physical distancing, with climate. It appears from this model that such measures, in combination with warm temperatures, actually might combine well to help slow the spread of this devastating virus. It’s a reminder that physical distancing will remain our best weapon into the summer to slow or prevent the spread of COVID-19. So, keep wearing those masks and staying 6 feet or more apart!
Caption: Here I am visiting the Ziika Forest area of Uganda, where the Zika virus was first identified in 1947. Credit: National Institutes of Health
A couple of summers ago, the threat of mosquito-borne Zika virus disease in tropical areas of the Americas caused major concern, and altered the travel plans of many. The concern was driven by reports of Zika-infected women giving birth to babies with small heads and incompletely developed brains (microcephaly), as well as other serious birth defects. So, with another summer vacation season now upon us, you might wonder what’s become of Zika.
While pregnant women and couples planning on having kids should still take extra precautions  when travelling outside the country, the near-term risk of disease outbreaks has largely subsided because so many folks living in affected areas have already been exposed to the virus and developed protective immunity. But the Zika virus—first identified in the Ziika Forest in Uganda in 1947—has by no means been eliminated, making it crucial to learn more about how it spreads to avert future outbreaks. It’s very likely we have not heard the last of Zika in the Western hemisphere.
Recently, an international research team, partly funded by NIH, used genomic tools to trace the spread of the Zika virus. Genomic analysis can be used to build a “family tree” of viral isolates, and such analysis suggests that the first Zika cases in Central America were reported about a year after the virus had actually arrived and begun to spread.
The Zika virus, having circulated for decades in Africa and Asia before sparking a major outbreak in French Polynesia in 2013, slipped undetected across the Pacific Ocean into Brazil early in 2014, as established in previous studies. The new work reveals that by that summer, the bug had already hopped unnoticed to Honduras, spreading rapidly to other Central American nations and Mexico—likely by late 2014 and into 2015 .
Caption: Incidence of dengue fever across Southeast Asia, 1993-2010. Note increasing incidence (red) starting about June 1997, which corresponds to a period of higher temperatures driven by a strong El Niño. At the end of the El Niño event, in January 1999, dengue incidence is much lower (green). Credit: Wilbert Van Panhuis, University of Pittsburgh
Just as the severity of the winter flu fluctuates from year to year in the United States, dengue fever can rage through tropical and subtropical regions of the world during their annual rainy seasons, causing potentially life-threatening high fever, severe joint pain, and bleeding. Other years—for still unknown reasons—dengue fizzles out. While many nations monitor the incidence of dengue within their borders, their data aren’t always combined to track outbreaks across wider regions over longer times.
Now, NIH-funded researchers and colleagues, reporting in Proceedings of the National Academy of Sciences , have linked an intense dengue epidemic that struck eight Southeast Asian countries starting in mid-1997 to high temperatures driven by the strongest El Niño event in recent times. El Niño is a complex, irregularly occurring series of climate changes in the Pacific Ocean with a global impact on weather patterns. This new insight into climatic factors associated with dengue transmission could enable better prevention measures, which may soon be needed because climatologists are predicting another strong El Niño event next year due to unusually high ocean temperatures in the equatorial Pacific.