The number of children admitted to hospital suffering from the world's most deadly vaccine-preventable disease has risen sharply.
More than 50% more youngsters went to an A&E department with acute pneumonia compared with a decade ago, according to new figures analysed by Save The Children.
Some 56,000 children were admitted to English emergency wards with the disease, the data shows.
Rates of admission for pneumonia, which a Sky News study found was the disease that kills the most people worldwide despite there being a vaccine that can prevent it, is highest in poorer areas, the charity found.
The disease, borne by bacteria, viruses or fungi, leaves children fighting for breath as their lungs fill with pus and fluid.
Children with weakened immune systems and those living in areas with high levels of air pollution are at greater risk of developing the disease.
The charity says that the levels of the disease in England should act as a worldwide alert that action is needed.
Kevin Watkins, CEO of Save the Children, said: "These findings show pneumonia is a disease that affects the poorest children worst of all, wherever they are in the world.
"But while British children almost always survive, millions of children in poor countries are dying for want of vaccines, a few pence worth of antibiotics, and routine oxygen treatment. With such simple solutions, no child should have to die from pneumonia regardless of where they live.
"This is a forgotten global epidemic that demands an urgent international response. The UK government must continue to invest in global efforts to tackle the pneumonia crisis so that children everywhere can access life-saving healthcare."
Pneumonia can be prevented with vaccines and treated with antibiotics that cost just 20p if diagnosed in time.
Globally, pneumonia claimed the lives of 800,000 children under the age of five in 2018, or one child every 39 seconds.
Despite the rising rates of infection in England, Save The Children found relatively few people realised it could be as dangerous as it is.
A poll for the charity by Opinium found only 4% of UK adults correctly identified pneumonia as the world's biggest infectious killer, with the largest share (34%) believing malaria caused the largest number of child deaths, followed by diarrhoea (18%) and measles (11%).
Catherine Sage's son, Edward, was rushed to hospital with severe pneumonia earlier this year at the age of eight.
An x-ray of his chest revealed his lung had completely collapsed.
Ms Sage, from Loughborough, said: "He woke up in the night gasping for breath. He was making a sound I'd never heard him make before. It was really scary.
"I knew people were hospitalised for pneumonia but I thought it was only really old people. I had no idea it could be so dangerous for young children. I was surprised how severely ill it made him."
In 2018, 27 children in England died from pneumonia.
The UK takes a leading role in improving access to vaccines and health services around the world, but tens of millions of children are still not vaccinated against pneumonia.
Children with severe cases of the disease may also require oxygen treatment, which is rarely available in the poorest countries to the children who need it.