A leading charity has warned that a rate of five new Ebola cases an hour in Sierra Leone means healthcare demands are far outstripping supply.
Save the Children said there were 765 new cases of Ebola reported in the West African state last week, while there are only 327 beds in the country.
Earlier, the World Health Organization (WHO) said two experimental vaccines were being fast tracked for use.
It is the world's worst outbreak of the virus, killing 3,338 people so far.
There have been 7,178 confirmed cases, with Sierra Leone, Liberia and Guinea suffering the most.
'Massively unreported'
Save the Children says Ebola is spreading across Sierra Leone at a 'terrifying rate', with the number of new cases being recorded doubling every few weeks.
It said that even as health authorities got on top of the outbreak in one area, it spread to another.
The scale of the disease is also 'massively unreported' according to the charity, because 'untold numbers of children are dying anonymously at home or in the streets'.
Earlier this month, Britain said it would build facilities for 700 new beds in Sierra Leone but the first of these will not be ready for weeks, and the rest may take months.
But Save the Children said that unless the international community radically stepped up its response, people would continue to die at home and risk infecting their family and the local community.
'We are facing the frightening prospect of an epidemic which is spreading like wildfire across Sierra Leone, with the number of new cases doubling every three weeks,' said Rob MacGillivray, the charity's country director in Sierra Leone.
Safety trials for two experimental vaccines are under way in the UK and US, the WHO said on Wednesday, and will be expanded to 10 sites in Africa, Europe and North America in the coming weeks.
It said it expected to begin small-scale use of the experimental vaccines in West Africa early next year.
Ebola virus disease (EVD)
Symptoms include high fever, bleeding and central nervous system damage Spread by body fluids, such as blood and saliva Fatality rate can reach 90% - but current outbreak has mortality rate of about 70% Incubation period is two to 21 days There is no proven vaccine or cure Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery Fruit bats, a delicacy for some West Africans, are considered to be virus's natural host
