Africa: Emergency Vaccine Response Has Cut Infectious Disease Deaths By Nearly 60 Percent Since 2000

Geneva — Researchers at Burnet Institute, in collaboration with Gavi, the Vaccine Alliance, have provided the world’s first ever look at the historical impact of emergency vaccination efforts on public health and global health security, with a comprehensive study of 210 outbreaks of five infectious diseases – cholera, Ebola, measles, meningitis and yellow fever – in 49 lower-income countries between 2000 and 2023.Analysis based on the study published this week in the British Medical Journal (BMJ) Global Health finds that, during this time period, emergency vaccination is estimated to have reduced cases and deaths by nearly 60% on average across these five diseases. For some diseases like yellow fever and Ebola, outbreak response vaccination efforts are estimated to have decreased deaths by 99% and 76% respectively. This impact from outbreak response is in addition to millions of deaths and cases averted by preventive and/or routine vaccination against the five diseases. In all cases, the study found emergency vaccination significantly reduced the threat of outbreaks expanding. The findings also underscored the importance of rapid outbreak response times and maintaining strong routine immunization coverage – especially in high risk settings – to prevent and minimize cases and deaths.

Many of the outbreak responses studied were funded by Gavi. Gavi-funded global stockpiles of cholera, Ebola, meningitis and yellow fever vaccines are accessible to all countries in the world, and their use for outbreak response is managed by the International Coordinating Group for Vaccine Provision, led by IFRC, MSF, UNICEF and WHO. In lower-income countries eligible for Gavi support – where these outbreaks are most likely to occur – Gavi fully funds the cost of doses, their delivery to affected communities, and outbreak response vaccination campaigns. The Alliance also provides this support for measles outbreak response in lower-income countries through the Measles & Rubella Partnership.

In total, the study found that vaccination in response to these 210 outbreaks generated nearly US$ 32 billion in economic benefits from averting deaths and years of life lost to disability. It noted this amount is a significant underestimate of overall savings, because it does not take into account outbreak response costs nor the social and macro-economic impacts of disruptions created by large outbreaks. For example, the 2014 Ebola outbreak, which occurred before the existence of an approved vaccine and saw cases imported around the world, is estimated to have cost West African countries alone more than US$ 53 billion.

“For the first time, we are able to comprehensively quantify the benefit, in human and economic terms, of deploying vaccines against outbreaks of some of the deadliest infectious diseases,” said Dr Sania Nishtar, CEO of Gavi, the Vaccine Alliance. “This study demonstrates clearly the power of vaccines as a cost-effective countermeasure to the increasing risk the world faces from outbreaks. It also underscores the importance of fully funding Gavi, so it can continue to protect communities in the next five years to come.”

UNPACKING THE RESULTS BY DISEASE

For each disease, researchers studied the lower-income country outbreaks with sufficient data to simulate a baseline range of observed and estimated cases and deaths, and where emergency vaccination had occurred. From there they modelled a counterfactual scenario without any outbreak response vaccination – and then calculated the number of cases, deaths and disability-adjusted life years (DALYs) that had been averted thanks to the vaccine response. The study also estimated the economic benefits generated from averting those deaths and DALYs, and examined how vaccination response had impacted the risk of large outbreaks. An analysis of what this means in terms of percentage reductions in cases and deaths, is below.

Ebola: Ebola is a rare but serious illness that presents a high health security risk, as demonstrated by the 2014 West African Ebola outbreak, which resulted in more than 11,000 deaths in the region and cases imported to countries around the world. While no approved vaccines existed in 2014, vaccines are now available to all countries in the world thanks to Gavi’s work incentivizing their development and establishing a global stockpile. Vaccines have proven highly effective at cutting cases and deaths in subsequent outbreaks, with high risk countries now protecting healthcare and other frontline workers in advance through Gavi-supported preventive vaccination efforts. The study looked at 7 Ebola outbreaks where vaccines were available as a response tool, finding that these efforts had reduced cases and deaths by 77% and 76% on average respectively – and significantly decreased the threat of large emergencies like the 2014 West Africa epidemic.

What’s next? In its next strategic period from 2026-2030 (Gavi 6.0), Gavi aims to maintain the global Ebola vaccine stockpile, for use by all countries, while also supporting the highest-risk countries with preventive vaccination of frontline workers.

Yellow Fever: While yellow fever is a highly deadly mosquito-borne disease that cannot be eliminated, the risk of outbreaks can be substantially reduced by immunising at least 60-80% of the at-risk population. With this goal in mind, Gavi has helped dramatically reduce the occurrence of large outbreaks by supporting countries to introduce the vaccine into routine immunisation and conduct mass preventive campaigns – protecting hundreds of millions of children and adults in the most at-risk countries. Since 2001, Gavi has also supported the global yellow fever stockpile to help countries respond to outbreaks. Across the 88 yellow fever outbreaks studied, researchers found that outbreak response vaccination had helped reduce cases and deaths by 98% and 99% respectively, on average. The study found the highest impacts occurred when campaigns were implemented with faster response times, and when they took place in settings with high yellow fever transmission and lower baseline immunity. This underscores the importance of both timely outbreak response as well as routine and preventive vaccination in preventing cases and deaths. Indeed, current yellow fever outbreaks in Africa are largely driven by countries with low routine coverage rates and where mass preventive vaccination last occurred 10-15 years ago.

What’s next? In its 6.0 strategic period, Gavi aims to support at-risk countries with targeted preventive vaccination to prevent the occurrence of future outbreaks and help bring ongoing outbreaks firmly under control – while maintaining support for routine immunisation in high-risk countries and ensuring that all countries around the world have access to emergency doses for outbreak response via the global stockpile. For example, countries in South America that are currently facing large outbreaks can access doses from the global stockpile and reimburse Gavi for costs.

Cholera: Cholera outbreaks occur primarily because people cannot access safe water, sanitation and hygiene (WASH) services and timely treatment. The majority of cholera cases can be successfully treated with oral rehydration salts, but rapid access is critical – often a struggle when the disease occurs amongst some of the most vulnerable populations where access to WASH infrastructure has been impacted by factors such as a lack of basic services, conflict, natural disaster, or displacement. When cholera outbreaks occur, emergency vaccination of affected populations plays a key role in bringing them under control. The study found that, across 40 cholera outbreaks between 2011 and 2023, on average vaccination helped reduce cases and deaths by 28% and 36% respectively. Historically, oral cholera vaccines have been used primarily as an emergency response tool, and have not been provided routinely. The study also found that – in the absence of the baseline of immunity that such routine vaccination would provide – very rapid response is critical to saving lives.

What’s next?In the long-term, ensuring access to WASH infrastructure must play a primary role in bringing endemic cholera under control. With the world experiencing an acute upsurge in outbreaks since 2021, cholera vaccines are now more in demand than ever before in history. However, rapid response is often difficult in the fragile settings in which cholera outbreaks tend to occur. This helps make preventive vaccination critical to cholera control, and thanks to long-term efforts to increase global vaccine supply, there are finally enough doses to make this a reality. From 2026 to 2030, alongside maintaining its support for outbreak response, Gavi is aiming to help cholera-endemic countries conduct targeted preventive vaccination.

Measles: Measles is highly infectious, and 95% coverage rates are needed to prevent outbreaks – making routine and preventive vaccination essential. However, achieving this high level of coverage can be challenging in many settings – inevitably leading to outbreaks. The study found that, over the last twenty years, measles vaccination in response to outbreaks in lower-income countries has reduced cases by 59% and deaths by 52%. Importantly, it also helped dramatically reduce the risk of large outbreaks – critical in settings where the population has less baseline immunity due to lower coverage rates.

What’s next? Like other vaccines, measles vaccine coverage rates in lower-income countries declined during the COVID-19 pandemic – leading to an increase in measles outbreaks. Gavi has been leading efforts to support countries to get back on track, including through preventive campaigns that have reached hundreds of millions of children since 2021. Outbreak response efforts have protected more than 35 million children since 2021. These efforts will continue in 2025, and during Gavi’s next strategic period, where the goal is to continue increasing measles vaccine coverage rates to prevent the occurrence of outbreaks.

Meningitis: With Gavi-supported routine and preventive vaccination having helped eliminate meningitis A outbreaks from Africa’s meningitis belt, the study focused on meningitis outbreaks caused by other strains – which represented the majority during the time period studied. During this time period routine and preventive vaccination against these other strains were not the norm. The study found that across 10 years, vaccination in response to these outbreaks reduced, on average, cases and deaths by 27% and 28% respectively. Similar to cholera, the study noted that in such a scenario where the general population is not protected through routine immunisation, the speed of response is a key determining factor of the overall impact of emergency vaccination efforts.

What’s next? The recent availability of a new multivalent conjugated vaccine – which protects against the five most prevalent meningitis strains and offers longer-lasting protection – has improved Gavi’s ability to support countries. The vaccine is part of the global stockpile and is already being used to respond to meningitis-C outbreaks. It also expands Gavi’s ability to support targeted preventive campaigns in high risk countries – which will reduce the overall burden and even offers the possibility of eliminating outbreaks of other meningitis strains in Africa. Later this year, Niger, which has experienced outbreaks for the last five years, will become the first country to conduct a nationwide preventive campaign with the multivalent meningitis vaccine.

PROTECTING GLOBAL HEALTH SECURITY THROUGH 2030

Gavi is currently seeking to fully fund its next strategic period from 2026 to 2030, Gavi 6.0. With the threat of infectious diseases on the rise, the Alliance aims to make its largest ever investment in health security. This includes maintaining the current global vaccine stockpiles while adding new stockpiles against diseases like mpox and Hepatitis E, and supporting targeted efforts to address the root causes of current outbreaks of yellow fever, Ebola, cholera, meningitis, and measles.

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