We all produce a natural protein in our bodies called granulocyte-macrophage colony stimulating factor (GM-CSF). This protein helps to produce cells in our lungs that provide a first line of defence against infection. Some studies have shown that an injection of GM-CSF can boost vaccines, but this has not been tested in older people receiving respiratory vaccinations.

Our aim is eventually to run a clinical trial in which people over 60 years old receive their vaccines with or without GM-CSF, to determine if giving GM-CSF with vaccines is safe and if it boosts vaccine efficiency.

We aim for our first trial to use a vaccine called Pneumovax 23, which is usually offered only once to people over 65 to protect against S. pneumoniae.

However, we cannot design such a trial until we know, in fine detail, the size of the response to Pneumovax 23 in people aged over 60.

Therefore, the purpose of the study is to provide such information so that we can go on to design the strongest possible clinical trial down the line, of Pneumovax 23 plus GM-CSF versus Pneumovax 23 plus placebo.

Sargramostim is a recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) which will be applied to participants’ cells in the laboratory (i.e. participants themselves do not receive Sargramostim in this study.