In a paper for Vaccine in November 2023 an international group of authors comment on the “unjust” distribution of “scarce” vaccines to mitigate infection harms and control the spread of mpox. They propose the application of the Fair Priority Model. Within this there are three key principles: 

  1. Benefit people and limit harm 
  2. Prioritise the disadvantaged 
  3. Equal moral concern 

In this article we examine how their proposition is presented within the paper and its implications for the global vaccine community. 

Mpox: still an urgent threat 

The paper reports that, by March 2023, over 86,000 cases of mpox had been confirmed worldwide since the start of the outbreak declared in 2022. In extreme cases, these incidences of mpox resulted in 112 deaths, with “about 15%” of these reported in African countries, where the disease is “historically endemic”.  

“Youth, pregnancy, and immunocompromise increase the risk of fatal complications, particularly in populations lacking adequate nutrition or good access to healthcare.” 
PEPV and PrEP 

The authors reflect that, because mpox has a long incubation period, post-exposure preventive vaccination (PEPV) can prevent infection in people who have recently been exposed. Furthermore, if infection does occur, PEPV can lessen the “severity and transmissibility” of disease. Vaccination can also serve as pre-exposure prophylaxis (PrEP) to at-risk individuals who haven’t recently been exposed. However, vaccine scarcity limits the “feasibility and scope” of this approach.   

As PEPV is effective against mpox, the authors tend towards prioritising PEPV in global allocation. Therefore, the initial phase of global allocation should “supply sufficient doses for PEPV based on a country’s currently documented case numbers” and projected growth. If vaccine supply is to exceed that which is needed for PEPV, a second phase for PrEP can begin.  

Vaccine nationalism 
“A recurring pattern during global outbreaks is for countries to rapidly obtain vaccines for their own populations, often to the detriment of other countries’ access.” 

Also known as “vaccine nationalism”, this phenomenon was observed during the 2009 swine flu outbreak and the COVID-19 pandemic, with “similar patterns” emerging for mpox. Although the authors refer to the potential of a pandemic treat to result in “better global cooperation”, there is a delay while we wait for negotiation to continue.  

Recognising that “countries can permissibly favour procuring vaccines for their own citizens” within reason, the authors describe current vaccine access as “objectionably disconnected” from the disease burden.  

“The international community can do better.”  

While calling on the community to “do better”, the authors ask a “fundamental ethical question”: 

“Which countries should be prioritised for the vaccines and in what quantities?” 
Fair Priority Model 

The Fair Priority Model is a framework for the equitable international allocation of vaccines. In Science in 2020 it was proposed as “ethically defensible and practical”. 

“The Fair Priority Model specifies what a fair distribution of vaccines entails, giving content to their commitments. Moreover, acceptance of this common ethical framework will reduce duplication and waste, easing efforts at a fair distribution. That, in turn, will enhance producers’ confidence that vaccines will be fairly allocated to benefit people, thereby motivating an increase in vaccine supply for international distribution.”  

Applied in this recent paper, the framework is focused to public health rather than research. While the authors recognise that “better data would improve the estimates of where doses can prevent the most harm” and inform better allocation, they state that there is no time to waste. Although improvements to the mpox evidence base are an “ethical imperative”, the equitable allocation of vaccines “must proceed simultaneously”.  

“The world cannot wait for more robust data before fairly allocating vaccines.” 

Highlighted in the paper are “three potential barriers to equitable allocation”: 

  1. High-income countries have used advance purchase agreements to secure priority access to newly manufactured vaccines, even for lower risk populations, excluding other countries that are interested in purchasing vaccines at market price. 
  2. Countries with stockpiled vaccines have hesitated to share their stockpiles. 
  3. Low-income countries that cannot afford vaccines lack an organised mechanism to access vaccines and largely depend on charity. 

Equitable allocation “could address these barriers”.  

The three principles of the Fair Priority Model (and an extra) 

Exploring the three principles in greater detail, the authors claim that harm prevention demands the prevention of “as much harm as possible per allocated dose”. In the context of mpox, which is “typically self-limiting”, vaccination can prevent or alleviate “weeks of painful symptoms”, which require isolation and can lead to hospitalisation. Both isolation and hospitalisation “compromise the ability” of many to maintain livelihoods. A reduction in transmission can also protect non-recipients. 

“Importantly, death is the most serious harm that vaccination prevents…death deprives someone of a future. The gravity of this harm is increase when people die earlier in life.” 

 The second principle addresses populations “whose disadvantages make them vulnerable” to the harms caused by the disease. For example, this may mean “preferentially allocating vaccines to countries with high prevalence of conditions” that increase the risk of severe complications.  

“Further preferential allocation may be appropriate as more evidence emerges concerning risk factors that worsen outcomes, such as lack of access to health care, poverty, or malnutrition.”  

The final principle, equal moral concern, requires “treating people the same when there are no morally relevant differences between them”. However, the authors emphasise that “this does not require identical treatment for everyone”.  

The authors consider a fourth ethical principle, “reciprocity”, which prioritises “those who have worked to alleviate the problem at hand. However, in the absence of “reasonable metrics” for contribution at an international level, and in the knowledge that this would favour high-income countries, the Fair Priority Model does not include reciprocity.  

Although the principles serve global vaccine allocation, the authors insist that their deployment in the paper “must be informed by the relevant features” of the current outbreak. Therefore, the suggested approach is “quite different” from the approach warranted for COVID-19.  

Phases and priorities 
“Within each allocation phase, countries should be prioritised based on the ethical principles.” 

Thanks to the “asymmetry” of cases and deaths, vaccination has the potential to “save substantially more lives per dose in the historically endemic countries than elsewhere”. However, it is interesting to note that the authors recognise that “vaccines should be allocated only where they will be effectively delivered”. Thus, some countries “might need outside assistance” with cold-chain infrastructure, diagnostics, and contact tracing to improve vaccine delivery.  

What about spread of endemicity? 

The paper also considers whether vaccine should be distributed to prevent the disease from becoming endemic in countries. After the experience of “first-time” outbreaks, some nations are “anxious”. However, “preventing endemicity is not intrinsically important”, and the reasons for preventing endemicity are already “given high priority” in the Model.  

What does this mean? 

The Fair Priority Model, as outlined in the paper, is a “means to ensure international distribution of vaccines is informed by robust ethical principles”.  

“The Fair Priority Model can provide a detailed framework on the sorts of factors that should affect which countries receive priority in vaccine allocation.”  

The concluding suggestion is that in future, “rather than reacting” to emergencies, the world “would be better served” if there was an institution that can use these principles. How would you apply the principles, and do you think this is an effective model to apply to mpox vaccine allocation? What about other vaccine strategies? 

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