DAVOS (Switzerland) • Ebola, Zika, Sars - a century after the "Spanish flu" killed 50 million people, humanity now risks a new wave of deadly diseases and, in today's globalised world, another such pandemic may be unavoidable, experts warned at the Davos summit this week.
"Pandemics are becoming a real threat to humanity," Mr Elhadj As Sy, secretary-general of the International Federation of Red Cross and Red Crescent Societies, told Agence France-Presse at the World Economic Forum in the Swiss resort town.
One Davos discussion, titled Are We Ready For The Next Pandemic?, was joined by experts including Dr Sylvie Briand, a specialist in infectious diseases at the World Health Organisation (WHO). "We know that it is coming, but we have no way of stopping it," she said.
This year marks the centenary of the worst epidemic in history: the so-called Spanish flu - an outbreak that experts say was imported to Europe by United States troops coming to fight in World War I.
Across the world, the disease killed more people in two years than the four years of fighting had.
Dr Richard Hatchett, director of the Coalition for Epidemic Preparedness Innovations (Cepi), said India lost 5 per cent of its population in 1918 - the only time in the country's history that its population declined.
A century on, a new flu virus is the risk that most worries experts.
"The flu is a respiratory virus that is easily transmitted and people can be contagious even before they show symptoms, so it is not easy to control," said Dr Briand.
Its numerous forms are also able to "marry" one another or bond with viruses from birds or pigs in potentially deadly new combinations.
Despite the development of anti-viral drugs, antibiotics and the first vaccines, two other flu pandemics erupted after the Spanish flu, in 1957 and 1968 - killing millions. More recent epidemics have reminded the world that it is still vulnerable to outbreaks. The Sars respiratory virus killed some 770 people in 2003.
"These past three years, there has been Ebola in West Africa, Zika in South America and, more recently, a plague epidemic in Madagascar" last year, said Mr Sy.
The Ebola haemorrhagic fever killed 11,000 in West Africa in 2014 and 2015. The disease also spread around the world after international travellers were infected.
"Humanity is more vulnerable in the face of epidemics because we are much more connected and we travel around much more quickly than before," said Dr Briand.
Dr Hatchett warned that specialists are still dealing with the consequences of Zika, a mosquito-borne disease which causes birth defects.
Experts also warned of the economic impact of outbreaks.
In 2015, hundreds of cases of the Mers respiratory syndrome cost South Korea US$10 billion (S$13.1 billion), Dr Hatchett said.
Billionaire philanthropist and Microsoft founder Bill Gates estimated in February last year that preparing to respond to a global pandemic would cost US$3.4 billion a year. The potential cost of one if the world is unprepared could be US$570 billion, he said.
Mr Gates is one of the main backers of the Cepi, which has overall funding of US$700 million and was launched at last year's Davos summit. The Cepi is seeking to develop treatments for three viruses for which there are currently none: Mers; Lassa fever, which is endemic in West Africa; and Nipah in Malaysia and Bangladesh.
Said Dr Briand: "At WHO, we are trying to prepare for a catastrophe, hoping to reduce the impact as much as possible."
Developing a vaccine against a new virus, however, is dangerous and can take up to six months, WHO says. It costs up to US$200 million, said Dr Peter Piot, director of the London School of Hygiene and Tropical Medicine.
That is not a big motivation for pharmaceutical laboratories, said Dr Hatchett, adding: "There is no commercial market for these products until there is an epidemic and then everyone wants the vaccine that doesn't exist."