Tackling yellow fever: UNICEF's efforts to strengthen diagnostic testing
UNICEF and partners are empowering countries to enhance disease surveillance to protect the most vulnerable children and their families.
Yellow fever, a mosquito-borne disease that causes more than 50,000 deaths annually, has long affected tropical and sub-tropical regions. With its potential to cause widespread outbreaks, it poses a significant threat to children’s health and well-being.
In the fight against this disease, UNICEF has taken the lead in procuring and delivering essential diagnostics supplies – and the results have been extremely positive. This boost to disease surveillance is helping to inform decision making for vaccination campaigns, transforming how we tackle yellow fever and its impact on communities.
Early detection, rapid interventions
Diagnostic tests are crucial for early detection and containment of disease outbreaks, significantly reducing the risk of death for the most at-risk people. In the case of yellow fever, testing is critical as part of disease surveillance efforts as it allows countries to identify outbreaks and take countermeasures, such as mass vaccination campaigns. This ensures vaccines – the best protection against yellow fever – are used in the right place at the right time.
Prior to 2018, there was insufficient investment in yellow fever testing capacity in Africa, even though 90 per cent of yellow fever cases were detected on the continent. The absence of yellow fever test kits approved by the World Health Organization (WHO) was also a major issue, as national public health laboratories needed to procure items from multiple suppliers to make up test kits, leading to delays of up to six months in getting results – a major bottleneck to the roll-out of public health measures.
These gaps in diagnostic capabilities meant countries faced a high risk of outbreaks and encountered difficulties in determining the appropriate timing and locations to vaccinate people, which put a strain on vaccine supply and increased the cost of vaccination campaigns.
A blueprint for development
Recognising the urgent need for improvements, Gavi, the Vaccine Alliance, called on UNICEF’s expertise in procurement and the WHO technical know-how to overcome issues in supplying yellow fever diagnostics to countries. With a financial commitment from Gavi between 2019 and 2025, UNICEF engaged with manufacturers and partners to bring affordable and quality-assured test kits to the market. The tests would then be delivered to 21 Gavi-supported countries in Africa that needed diagnostics the most.
In late 2020, a major milestone was achieved when UNICEF began shipping the first bundled ELISA yellow fever test kits – a highly sensitive test that detects and measures proteins or antibodies. It contained all the products necessary for a laboratory to test for yellow fever, freeing up much more of the laboratories’ time to test instead of spending it on inventory management and cumbersome ordering processes.
The results were impressive. In 2017, laboratories were only capable of testing 80 per cent of the samples they received, which increased to 98 per cent in 2022. This meant that countries were less likely to miss yellow fever outbreaks than in the past – a big help to public health systems on the frontline of detecting the virus.
Evolution of tests
Building on the achievements of this first stage of the diagnostics project, the overall partnership, which includes FIND, Gavi, UNICEF, the US Centre for Disease Control and Prevention (US CDC) and WHO, expanded its efforts to include additional diagnostic tools for yellow fever. A major development occurred in 2022 when molecular diagnostics (PCR) tests were introduced to UNICEF’s Supply Catalogue. This more advanced technology improved laboratories’ ability to test swiftly and accurately, while also laying the foundation for future developments in disease surveillance and response.
“The enthusiasm we felt at the start of this project did not fade in front of many challenges posed by the COVID-19 pandemic,” says Afrora Striniqi, Contracts Specialist in UNICEF Supply Division’s Health Technology Centre. “A steady stream of deliveries was sent to countries throughout this time. We were also trying to build on the initial success of bundling test kits and move towards the addition of molecular diagnostics, and we did it.”
Since 2020, UNICEF has delivered almost 80,000 ELISA and PCR tests to 21 countries, helping to reduce the time needed to complete and confirm a yellow fever outbreak or the expansion of a new one by 70 per cent.
"The project has thrived because of excellent collaboration."
UNICEF continues to support yellow fever surveillance activities by introducing new and improved diagnostics products. An enhanced ELISA test and a rapid detection test, recently approved by WHO, will be available for countries to procure in late 2023.
“The project has thrived because of excellent collaboration,” adds Striniqi. “Between Gavi's advocacy and funding, UNICEF's supply and logistics management, WHO's technical expertise, and the US CDC’s and FIND's scientific research, we’ve made huge strides in protecting children and families from yellow fever. Regional and national labs that provided valuable feedback and technical inputs deserve our thanks as they really boosted the scale of our efforts.”
This collaboration ultimately serves to achieve the goals of the Eliminate Yellow fever Epidemics (EYE) Strategy, which was launched in 2017 and aims to protect almost 1 billion people from yellow fever by 2026. Today, 226 million people in Africa have been protected through vaccination campaigns against the disease – a figure that has doubled in the past five years. The investment in surveillance diagnostics, and enhancing targeted, risk-informed vaccine distribution, contributes considerably to this success.
Next in line: cholera
The impact of UNICEF and its partners’ work extends far beyond yellow fever. The success of tackling this disease can be replicated to address other major public health concerns. Cholera, another vaccine-preventable disease, is set to benefit from the pioneering development of bundling all the critical supplies a country needs to test rapidly and make interventions. By using the lessons learned and adapting the model from yellow fever, UNICEF aims to improve surveillance, diagnostics, and vaccination programmes for a range of diseases.
While the significance of this work lies clearly in the immediate impact of disease control, it also has other long-term implications for children's lives. Perhaps most significantly, by swiftly identifying yellow fever outbreaks, vaccines can be effectively allocated from stockpiles, ensuring that resources are directed where they are most needed. This strategic approach prevents unnecessary vaccine wastage, making the best use of available resources and ensuring the health and future of vulnerable populations.
