The Global Alliance for Vaccines and Immunisation (Gavi) has agreed to buy 200 million doses of Johnson & Johnson's (J&J) Covid-19 vaccine, as it seeks to fill a big shortfall in the Covax vaccine-sharing programme caused by India suspending exports, Reuters reports.

"As a one dose vaccine, the J&J vaccine has particular relevance for places with difficult infrastructure, making it a very important addition to the portfolio," Gavi CEO Seth Berkley said in a statement announcing the signing of an advanced purchase agreement with the US drugmaker.

Gavi said that the goal was to have the new J&J doses available in 2021, for distribution to both self-financing participants of Covax as well as poorer countries.