A coalition of governments and charities has committed $460m to speed up vaccine development for Mers, Lassa fever and Nipah virus.
They are asking funders at the World Economic Forum Davos for another $500m.
The Coalition for Epidemic Preparedness Innovations (Cepi) aims to have two new experimental vaccines ready for each disease within five years.
New vaccines usually take about a decade to develop and cost hundreds of millions of dollars.
The Ebola outbreak in West Africa, closely followed by the Zika epidemic in Latin America, exposed just how "tragically unprepared" the world is for new outbreaks.
Jeremy Farrar, director of the Wellcome Trust, one of the founding members of Cepi, said: "Before the 2014 outbreak we only had very small Ebola epidemics that were in isolated communities that we were able to control.
But in the modern world with urbanisation and travel, 21st Century epidemics could start in a big city and then take off the way Ebola did in West Africa.
We have to be much better prepared.
Ebola killed more than 11,000 people in Liberia, Sierra Leone and Guinea.
The arrival of the Zika virus in Brazil in 2015 has left thousands of children brain-damaged.
During both outbreaks, there were no treatments or vaccines to prevent people getting sick.
Scientists scrambled to resurrect research on these obscure diseases.
Effective vaccines were eventually developed during the Ebola outbreak, but only as it started to wane.
Nevertheless, governments, scientists and regulators all came together with unprecedented speed, and managed to expedite the notoriously complex development and regulatory processes.
Cepi wants to continue that momentum and develop vaccines for other viruses so that by the time an outbreak hits, experimental vaccines are ready to be sent to affected areas for large human trials that can establish how effective the vaccine is.
Lassa, Middle East Respiratory Syndrome (Mers) and Nipah virus are "top of the list" of 10 priority diseases that the World Health Organization (WHO) has identified as potentially causing the next major outbreak.
Dr Marie-Paule Kieny, assistant director-general of the WHO, said: Besides the known threats - such as Ebola and others - there are also all those viruses that are known but are thought to be very benign.
She said they could mutate and become more dangerous for humans.
Then there are the things that are completely unknown to us at the moment, said Dr Kieny.
The lottery of viruses that could hit us next makes it very difficult to plan for the future.
Pharmaceutical companies aren't lining up to invest in these little-known viruses because there is no commercial market for them.
However, some have come on board with this new alliance, including GSK and Johnson and Johnson.
We've got lucky so far, said Jeremy Farrar, because recent outbreaks haven't become airborne.
But he said a far more contagious version of an Ebola like virus could emerge.
I could cough it over you today and you could cough it over someone tomorrow and it could spread very quickly.
That puts the world in a very vulnerable place.
: 2017-01-21 04:56:18 | : 662