Billionaire philanthropist Bill Gates has warned that the world is "vulnerable" to a quick-spreading deadly outbreak of an illness like flu.
Mr Gates said that Ebola and Zika outbreaks have exposed weaknesses in international efforts to swiftly tackle health crises, and said that the development of new drugs could also be improved.
He told the BBC Radio 4 Today programme: "When we've seen Ebola or even now Zika, we realise we still haven't done enough.
"Our ability to create new drugs and vaccines quickly where we have an emerging disease, our emergency response system where we get people in and try and stop these epidemics - we don't have a strong enough system."
He said that countries are grappling with ensuring that regulatory, liability and organisational boundaries do not slow down responses to health crises, adding: "I cross my fingers all the time that some epidemic like a big flu doesn't come along in the next 10 years.
"I do think we'll have much better medical tools, much better response, but we are a bit vulnerable right now if something that spread very quickly, like a flu that was quite fatal.
"That would be a tragedy, and new approaches should allow us to reduce that risk a lot."
The Microsoft founder, whose foundation has pumped billions into vaccines and improving health systems in developing countries, said that greater global cooperation is needed when it comes to new drugs and tackling outbreaks.
If wealthy countries fail to step up and help, he cautioned, then deadly epidemics will spread across the world.
Mr Gates said: "So it's not just the humanitarian goal here, it's strong self-interest that we want global health security."
England's chief medical officer, Dame Sally Davies, rated the NHS's preparedness for a major flu outbreak at "seven or eight", but warned that the economy and social care sectors would face major challenges.
She said: "But it's not just the NHS, the NHS looks after sick patients, it's how would our social care system cope with people who weren't ill enough to be in hospital but need extra support?
"It's how would our economy cope if a large proportion are too ill to work where we have a just-in-time ordering policy for delivery of food, petrol, whatever?
"And if you think about the issues that could happen here if we had a recurrence of the 1918 type flu, then what would it be like in middle and low income countries where they don't have the health systems to look after the patients?"
She said Britain is "very well prepared" with stockpiles and an agreement to buy flu vaccine if a pandemic breaks out, but she said it would take at least six months for the right vaccine to be found and distributed to the public.