WHO Endorses First New Malaria Vector Control Tool in Four Decades as Spatial Repellents Show 56% Protection Rate
Key Insights
The World Health Organization has issued its first recommendation for a new malaria (search) vector control tool in over 40 years, endorsing spatial repellents (search) that provide an average 56% protection against mosquito bites.
Clinical trials funded by Unitaid (search) demonstrated that spatial repellents (search) reduced malaria (search) cases by one-third when used alongside insecticide-treated nets (search), leading to WHO's conditional recommendation in August.
Three spatial repellent products are now available, with Guardian (search) offering up to one year of protection, addressing critical gaps as traditional vector control methods face declining effectiveness due to insecticide resistance.
The World Health Organization has issued its first recommendation for a new malaria (search) vector control tool in more than four decades, endorsing spatial repellents (search) that demonstrate significant protective efficacy against mosquito-borne diseases. The WHO's conditional recommendation, announced in August, marks a major milestone in expanding the malaria prevention toolbox as traditional methods face declining effectiveness.
Clinical Evidence Drives WHO Recommendation
The WHO recommendation is largely based on evidence from Unitaid (search)'s AEGIS (Advancing Evidence for the Global Implementation of Spatial Repellents (search)) project, led by the University of Notre Dame. A clinical trial conducted in Kenya clearly demonstrated that spatial repellents, when used alongside insecticide-treated nets (search), reduced malaria (search) cases by one-third.
Research analyzing 25 years of data and examining 1.7 million mosquitoes found that spatial repellents (search) provided an average protection of 56%, preventing more than half of the bites that would have occurred without the device. The tool protects against all types of mosquitoes that carry disease, although with varying levels of efficacy.
"We finally have a new way to protect against mosquito bites, especially one that fills in some of the gaps of our existing methods," said Ingrid Chen, PhD, MS, an associate professor of epidemiology and biostatistics at UCSF and the first author of the research published in eBioMedicine. "It's lightweight, affordable, and easy to use, so it can be used to help save lives in all parts of the world."
Addressing Critical Gaps in Vector Control
Vector control tools such as insecticide-treated nets (search) and indoor residual spraying remain a cornerstone of the global malaria (search) response, helping to avert hundreds of millions of cases in malaria endemic countries. However, their effectiveness is declining as mosquitoes become increasingly resistant to insecticides, evolve their behavior, or expand their range due to urbanization, climate change, and other factors.
Spatial repellents (search), also called spatial emanators, are designed to be hung on walls indoors and gradually release active ingredients into the air that kill mosquitoes or prevent them from biting. This intervention may prove particularly useful in providing protection when people are not under a net or where other tools are hard to implement.
The devices use chemicals similar to those in treated bed nets, which are considered safe, but in a more volatile form. Because they don't come into direct physical contact with people, spatial repellents (search) can be more easily updated with different insecticides, helping to keep pace with insecticide resistance.
Product Availability and Market Access
WHO has issued quality approval called prequalification for two spatial repellent products, Mosquito Shield (search) and Guardian (search), manufactured by SC Johnson & Son, Inc. (search) This essential step enables international procurement agencies to purchase the products and help expand access for malaria (search)-affected communities.
Three products are currently available: BiteBarrier (search), the first to be sold in the U.S., works for up to 21 days. Mosquito Shield (search) is effective for about 30 days, while Guardian (search), the most long-lasting of the three, can last up to one year, providing a cost-effective and convenient option for long-term protection.
Expanding Research Investment
Building on these results, Unitaid (search) is launching a new $18 million investment to generate further evidence to expand the potential use of spatial repellents (search), including as a standalone intervention and in diverse settings. The five-year project Catalyzing the Adoption of a Novel Vector Control Toolbox (CANVeCT) will be led by the Cameroon-based Centre for Research in Infectious Diseases (search) (CRID) in collaboration with the Liverpool School of Tropical Medicine (LSTM) and the London School of Hygiene and Tropical Medicine (LSHTM).
The project, implemented in Cameroon, will generate additional evidence to inform the evolution of WHO's recommendation for the use of spatial repellents (search), while also exploring their effectiveness in humanitarian settings. Determining whether spatial repellents work as stand-alone tools is particularly important amid deepening global funding cuts, making layering multiple interventions increasingly unaffordable for most national malaria (search) programs.
Global Health Impact
In 2023, malaria (search) killed 597,000 people, primarily children under five years old, in sub-Saharan Africa. The WHO aims to cut malaria mortality rates by at least 90% compared to 2015 levels and to eliminate the disease in at least 35 countries by 2030. However, progress has slowed in recent years due to the COVID-19 pandemic, limited funding, and the growing issue of insecticide resistance.
There are over 40 species of mosquitoes that transmit malaria (search), each with distinct biting and resting habits. The Anopheles mosquito primarily bites at night, while the Aedes mosquito, which carries dengue (search) and Zika (search), bites during the day. Spatial emanators can be used day and night and do not require heating or electricity, making them easy to use in remote areas in Africa, South America, and Southeast Asia, where malaria is prevalent.