It has been six years since the start of the COVID-19 pandemic, but one question remains relevant: who should be first in line when vaccines are scarce? Wageningen researchers Nazli Gul and Sander de Leeuw propose prioritising socioeconomically vulnerable groups.
When COVID-19 vaccines first became available, supply was limited and governments had to make difficult choices. In most countries, priority was based on medical risk. Older people, healthcare workers and those with underlying conditions were vaccinated first.
New research by Wageningen University & Research experts Nazli Gul and Sander de Leeuw revisits this approach. They ask whether it was not only effective, but also fair, and whether incorporating social inequality into vaccine allocation could have saved more lives.
Health risks are not evenly distributed
The pandemic did not affect everyone equally. People living in poverty, crowded housing or insecure jobs faced higher exposure to the virus and more severe outcomes. This pattern was observed across countries, including the UK, the United States and Brazil.
As Gul explains, "The pandemic did not create inequality. It revealed what was already there." She adds that even outside crisis situations, "when resources are limited, the most deprived are the least likely to benefit." This suggests that social vulnerability should play a role in allocation decisions more broadly, not only during pandemics.
Despite this, most vaccination strategies focused narrowly on medical vulnerability. Socioeconomic factors were rarely included in formal allocation models.
A smarter way to prioritise
To explore alternatives, Gul and De Leeuw developed a computer model using detailed data from England. They simulated the first 600 days of the pandemic and tested different vaccination strategies.
Their proposed solution is a "threshold policy". Within each age group, individuals living in more vulnerable socioeconomic conditions are prioritised until a certain share of that group is vaccinated. Only then does vaccination continue with less vulnerable individuals of the same age.
The model shows that a threshold of around 70 percent offers the best balance. It protects vulnerable groups while avoiding delays due to vaccine hesitancy or logistical barriers.
A common concern is that adding social criteria makes vaccine allocation too complex. Gul responds directly to this critique: "Our approach does not require identifying or profiling individuals. It uses area-level deprivation data that governments already collect." In practice, "a postcode can determine priority eligibility, not a person's file." According to her, "the added complexity is minimal, but the lives saved can be significant."
"Our approach does not require identifying or profiling individuals. It uses area-level deprivation data that governments already collect."
- Nazli Gul
Fewer deaths, more fairness
Strategies based solely on medical risk do not reduce deaths as effectively as expected and do little to improve fairness. By contrast, the threshold-based approach both lowers overall mortality and leads to a more equitable distribution of vaccines and outcomes.
This challenges the assumption that fairness and effectiveness are in tension. In this case, taking inequality into account improves both.
At the same time, the impact of such strategies depends on demographic context. In younger populations with higher levels of natural immunity, the benefits are smaller. In populations with more vulnerable groups, the gains are more pronounced.
The researchers also emphasise that vaccination alone cannot solve structural inequality. Long-term improvements in living conditions remain essential for reducing health disparities.
Lessons for future pandemics
The study offers an important lesson for future crises. As Gul puts it, "do not wait until vaccines are abundant to think about equity." Their findings show that "prioritising socioeconomically vulnerable groups early, even partially, both saves more lives and distributes protection more fairly."
The broader message is clear. "In a pandemic, treating everyone the same is not always fair," Gul concludes. "And as our results show, it is not always the most effective approach either."
Operations Research and Logistics
Operations Research and Logistics, led by Sander de Leeuw, aims to contribute to Operations Research and Logistics Management in agrifood and biobased supply chains.
