British volunteers are helping deliver life saving vaccinations to children in the world's poorest countries.
r Shona Johnston helps staff the crowded wards of the Ola During Children's Hospital in Freetown, Sierra Leone, where the nation's most desperately ill children are sent for treatment.
She has seen the benefit brought by the Sierra Leonean government's commitment to provide free healthcare and vaccination during her eight-month stint in the capital city's bustling east end, a world away from her roots in Lerwick, in the Shetland Islands off the north coast of Scotland.
Many of the children Dr Johnston treats suffer from malnutrition, pneumonia, or diarrhoea. Vaccinations against these illnesses, which account for over 40% of child deaths in the west African state, would save many lives.
The 31-year-old paediatrician divides her time between providing clinical care for the children and training up the Sierra Leonean medical students who are about to graduate.
She said: "It is very very different to working in a British hospital. For one thing, in the UK there would be more doctors and a lot more equipment. It is very busy and chaotic, but it is a fun place to work."
The hospital has currently about 200 children admitted and is treating about 80 cases a day. The caseload is handled by six doctors, including Dr Johnston and Dr David Baion, the medical superintendent and paediatrician at the hospital, and three shifts of nurses.
In January, with Global Alliance for Vaccines and Immunisation (GAVI) support, Sierra Leone introduced a new vaccine that will protect children from pneumococcal disease, the leading cause of pneumonia.
The Ministry of Health and Sanitation in Sierra Leone hopes its application to GAVI for support in introducing rotavirus vaccines, which protect children against the leading cause of severe infant diarrhoea, will be successful.
At the pledging conference in London on Monday, GAVI will make the case that between 2011 and 2015, it will need an additional £2.3 billion in additional new donor contributions, in particular to fund pneumococcal and rotavirus vaccine introductions in more than 40 countries where they are most desperately needed, by 2015. If fully funded, GAVI could avert another four million deaths from 2011 to 2015.