In their #MissingType campaign, London-based PR company Engine Group and NHS Blood & Transplant, tried to get people’s attention by eliminating the letters A, B and O from public landmarks and participating brands across the globe.

Image by Sydney Opera House via Instagram

Image by Iamsterdam via Twitter

Image by Marmite via Twitter

The (missing) letters – A, B and O – are used to identify the main blood types. The campaign hoped to reverse a decline in new donors and encourage blood donations to meet the need for blood in the future.

According to an article on NPR the NHS said: “The shortage of new donors is a worldwide phenomenon… A survey of blood services participating in the Missing Type campaign found the number of first-time donors per year had dropped more than 27 percent between 2005 and 2015.”