If we speak about low-income countries (LICs), I'd say that the World Bank and the International Monetary Fund make certain positive effects. For instance, the goal of the World Bank is to decrease the poverty degree of such countries by implementing certain measures such as providing loans and consulting, while IMF does that by discussing economics issues with countries' authorities and adjusting their financial policies.
For example, the World Bank Group spent $12 billion to support the struggle with the new coronavirus COVID-19. IMF, on the other hand, helped Guinea, Liberia, and Sierra Leone - countries that suffered the most from the Ebola epidemic - with $100 million in 2015.
The sad thing is that the two organizations cannot always control that the funds reached their goal (for instance, medical and healthcare facilities) to the full extent as it was planned.