Greater income inequality linked to worse HIV outcomes

IMF Photo/James Oatway. Creative Commons licence.

Countries with greater income inequality have more new HIV infections and more deaths from both AIDS and COVID-19, a recent study has found.

Governments’ responses to pandemics have often focused heavily on individual behaviour, encouraging or mandating behaviour change to limit the spread of infection. However, much less attention has been paid to how broader social determinants impact health outcomes for these global crises.



Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

statistical significance

Statistical tests are used to judge whether the results of a study could be due to chance and would not be confirmed if the study was repeated. If result is probably not due to chance, the results are ‘statistically significant’. 


The Joint United Nations Programme on HIV/AIDS (UNAIDS) brings together the resources of ten United Nations organisations in response to HIV and AIDS.

Income inequality has been highlighted as a key factor leading to negative health outcomes. It results in health disparities both within and between countries by shaping conditions that make people more vulnerable to contacting an infection such as HIV or dying of an AIDS-related illness.

Pandemics magnify this impact, as income inequality is linked to a range of factors that affect pandemic outcomes – including limited access to good quality healthcare and housing for large parts of the population, a lack of social cohesion and an absence of effective public health responses.

The study

Professor John Ele-Ojo Ataguba, from the African Health Economics and Policy Association, and colleagues at UNAIDS investigated the impacts of income inequality on pandemic outcomes in a multi-country study published in BMJ Global Health.

They considered three main outcome measures:

  • New cases of HIV per 1,000 people
  • Deaths from AIDS-related complications per 100,000 people between 2000 and 2021
  • Excess deaths caused by COVID-19 per 100,000 people in 2020 and 2021.

For the HIV and AIDS analyses, 217 countries were included, with 151 included for the COVID-19 analysis.

The Gini index of the preceding year was used as a measure of income inequality at the country level. This index represents how much income inequality is present, ranging from 0 (perfect equality) to 1 (total inequality). Importantly, the Gini index does not indicate how rich or poor a country is but focuses on how much income inequality is present.

The researchers considered three different samples: all countries, African countries as a group, and a sample excluding African countries. This was done to see if there were differences in how income inequality impacted health outcomes across the different groupings, based on UNAIDS regional classifications.

Additionally, the researchers considered each country’s health expenditure and their income classification category according to the World Bank. This allowed them to separate out the effects of income level and healthcare expenditure and focus specifically on the impacts of income inequality. While these are related determinants, income inequality focuses on the unequal distribution of wealth within a country, as opposed to an absolute value, such as Gross Domestic Product per capita, for instance.


The average Gini index for all countries in the study from 2000 to 2021 was 0.57, ranging from a low in Hungary (0.37) to a high in Botswana and Namibia (0.78). Average annual per capita health expenditure for this period was just under $1,000.

In terms of health outcomes, the average number of AIDS-related deaths was 45 per 100,000 people, while new HIV infections averaged at 0.8 per 1,000 people between 2000 to 2021. For the last two years of this period, the average excess COVID-19 deaths were estimated at 73 per 100,000 people.

"More unequal countries have a higher HIV incidence, AIDS mortality and COVID-19 excess deaths than their more equal counterparts."

In terms of HIV incidence, higher levels of income inequality were significantly associated with increases in new HIV infections in the following year (p < 0.01). While this was true for all three geographical groups that the researchers looked at, the impact of income inequality on new HIV infections was more pronounced in African countries than in the rest of the world, likely due to higher overall numbers of HIV in sub-Saharan Africa.

To illustrate this, a 25% reduction in the Gini index (a reduction in inequality) would reduce the HIV incidence by 0.14 infections per 1,000 people globally and by 0.29 infections in the sample excluding Africa. For African countries, this same reduction in income inequality would be associated with a reduction of 2.11 infections per 1,000 people in the following year.

A similar pattern was seen for AIDS-related deaths – increases in income inequality resulted in a significant association with increases in deaths in the following year (p < 0.01). However, in this instance, the effect was most pronounced for non-African countries: a 25% reduction in income inequality would be associated with a reduction in AIDS-related deaths of 6.58 AIDS-related deaths per 100,000 people globally, 11.45 deaths in African countries and 17.39 deaths in the sample excluding African countries.

For COVID-19 excess deaths, a statistically significant positive relationship between increasing income inequality and an increase in excess deaths was found for the global sample and the sample excluding African countries (p < 0.05). However, while the there was a positive relationship between income inequality and COVID-19 excess deaths for African countries, it was not statistically significant.


The researchers caution that, while their analyses indicate a strong association between greater income inequality and negative pandemic outcomes, they did not assess causality. Additionally, other dimensions of inequality – such as gender, race, and sexuality – which often intersect with income inequality, were not captured.

Nonetheless, their findings provide compelling evidence for the role of income inequalities at a global level. “COVID-19 excess deaths, HIV incidence and AIDS mortality are significantly associated with income inequality globally—more unequal countries have a higher HIV incidence, AIDS mortality and COVID-19 excess deaths than their more equal counterparts. Income inequality undercuts effective pandemic response,” they conclude.

“There is an urgent need for concerted efforts to tackle income inequality and to build pandemic preparedness and responses that are adapted and responsive to highly unequal societies, prioritising income inequality among other social determinants of health.”


Ataguba JE et al. Income inequality and pandemics: insights from HIV/AIDS and COVID-19 – a multicountry observational study. BMJ Global Health, 8:e013703, 2023 (open access).

Full image credit: IMF Photo/James Oatway. Available at under Creative Commons licence CC BY-NC-ND 2.0.