UK Investment in Gavi, the Vaccine Alliance (2021-2025) Gavi, the Vaccine Alliance (Gavi) supports vaccine delivery in 57 of the world's poorest countries. Gavi immunises children against vaccine preventable diseases including measles, rubella, meningitis, cervical cancer, pneumonia and diarrhoea. Gavi has played a significant role in the recent halving of global child mortality. Gavi targets reaching those in hard to reach areas, the poorest, and the most marginalised. It has a major global market shaping role for vaccines to negotiate lower prices for low-income countries and incentivising new vaccines.