LONDON (Reuters) – British Prime Minister Boris Johnson will host a global vaccine summit on Thursday, urging nations to pledge funding for vaccinations against infectious diseases to help the poorest countries tackle the coronavirus crisis.

Representatives of more than 50 countries, including 35 heads of state or government, will come together virtually in London to raise funds for the GAVI vaccine alliance, a public-private global health partnership.

The summit aims to raise at least $7.4 billion (6 billion pounds) for GAVI to immunise a further 300 million children in the world’s poorest countries by 2025 against diseases such as polio, diphtheria and measles.

“Just as the UK is the single biggest donor to the international effort to find a coronavirus vaccine, we will remain the world’s leading donor to GAVI, contributing 1.65 billion pounds over the next five years,” Johnson said in a statement.

“I urge you to join us to fortify this lifesaving alliance and inaugurate a new era of global health cooperation, which I believe is now the most essential shared endeavour of our lifetimes.