There is still no Ebola vaccine 40 years after the disease first emerged because it previously affected only poor African nations, the head of the World Health Organisation has said.

In unusually strident comments, Dr Margaret Chan, the director-general of the WHO, attacked drug companies and said that the reason clinicians were “empty-handed” was because “a profit-driven industry does not invest in products for markets that cannot pay”.

She said that long-standing WHO complaints about the lack of investment in both vaccine development and the healthcare systems of poor states had “fallen on deaf ears for decades”. But the current global Ebola panic put the arguments “out there with consequences that all the world can see, every day, on prime time TV news”.

Speaking to the WHO’s regional committee for Africa in Benin, she said: “Ebola emerged nearly four decades ago. Why are clinicians still empty-handed, with no vaccines and no cure?"

She continued: “Because Ebola has historically been confined to poor African nations. The R&D incentive is virtually non-existent. A profit-driven industry does not invest in products for markets that cannot pay.”

In recent months several prototype Ebola vaccines have been rushed through development, a process which usually takes up to 10 years. But even the most promising will not have completed testing for safety and efficacy before the end of next year.

Nearly 5,000 people have died from Ebola in West Africa, and there are signs that the spread of the virus is still increasing in Sierra Leone, although it appears to be slowing down in the worst-hit country, Liberia.

Potential vaccines must first be tested for safety. The most promising candidate, GlaxoSmithKline’s ChAd3, is currently being tested at the Jenner Institute in Oxford, the National Institutes of Health in Maryland, USA and in Mali.

It has been funded by a £2.8m grant from the Wellcome Trust, the Medical Research Council and the UK Government. GSK has begun manufacturing additional doses ahead of the outcome of trials, with 10,000 doses potentially available by the beginning of next year. If proved safe, the efficacy of the vaccine will be tested by immunising healthcare workers combating Ebola in West Africa.

The men and women on the frontline against Ebola and other hazards Show all 6 1 /6 The men and women on the frontline against Ebola and other hazards The men and women on the frontline against Ebola and other hazards Linda Dixon, 60, leads research into African swine fever at the Pirbright Institute in Surrey "For more than 25 years I've been trying to develop a vaccine for the African swine fever virus, which causes death in domestic pigs, and has symptoms quite like Ebola. It came from East Africa in the 1920s and was transmitted to Georgia in 2007 via food from shipping that was fed to pigs. It has now spread to neighbouring countries and this year entered the EU via Poland, Lithuania, Latvia and Estonia. It's difficult to eliminate because it also infects wild boar, which populate large parts of Europe." David Vintiner The men and women on the frontline against Ebola and other hazards Simon Woodmore, 45, is a paramedic and operations officer for London Ambulance Service's Hazardous Area Response Team (Hart) "I have a helmet for all occasions – five in all – as well as an array of outfits, including breathing apparatus and gas-tight suits, respirators and chemical protective suits. My job is to put paramedics where historically they could not have worked. We were born out of the Tokyo subway sarin attack in 1995, and have been running as Hart since 2006. There are 94 of us in London dealing with chemical, biological and radiological incidents, as well as building collapses and floods." David Vintiner The men and women on the frontline against Ebola and other hazards Simon Woodmore, paramedic and operations officer "We've always dealt with contagious diseases and work with the Royal Free Hospital London high-level isolation unit to transfer confirmed cases, which fortunately is rare. A lot of it is communicating with the patient in a caring and compassionate way, which can be difficult when you're in full gear. There is an increased awareness of Ebola, but it's about reinforcing the processes we already have in place. Any personal risk is mitigated by our training and equipment." David Vintiner The men and women on the frontline against Ebola and other hazards Benjamin Black, 33, is a specialist registrar in obstetrics and gynaecology for Médecins Sans Frontières (MSF) "In June I travelled to Sierra Leone, where one in 21 women of reproductive age dies in childbirth. This was my first mission, and the reason I got into medicine. I had my eyes wide open to Ebola; though it was still in its early days and concentrated across the border in Guinea, within days I had my first suspected Ebola cases in maternity. It was happening." David Vintiner The men and women on the frontline against Ebola and other hazards Benjamin Black, Médecins Sans Frontières "You need a healthy amount of fear to be safe, as well as protocol and organisational back-up. The greatest fear then is how long you can keep getting it right. There is also a huge psychological element. I checked my temperature daily, but in a hot, humid country there's a constant feverish feeling anyway. We had scares and one of our national nurses was infected, probably in the community. He sadly died and it had a huge impact on the team." David Vintiner The men and women on the frontline against Ebola and other hazards Lisa Jameson, 29, is a National Institute for Health Research doctoral research fellow for Public Health England, based at the Porton Down facility in Wiltshire. She specialises in emerging viruses "I was in the field watching patients come into the isolation centre next to us, often with their families. Sometimes they'd be walking and talkative, then die that night. It was tough but we were so busy, and being there made it feel like we were making a difference. When I got home after a month, I felt a sense of guilt that I was able to walk away. I'll almost certainly be going back." David Vintiner

Trials of another promising vaccine, VSV, are due to take place in Europe, Gabon and Kenya. Developed by the Public Health Agency of Canada, a £3.1m grant from the Wellcome Trust will allow safety information to be gathered, with 800 vials of the vaccine donated by the Canadian government.

The virus was first discovered in 1976, and there have been more than 20 Ebola outbreaks since then. However, they have all been on a much smaller scale to the current epidemic, meaning that until now there had been little momentum behind efforts to develop a treatment or vaccine.

The failure of governments and the international pharmaceutical industry to develop one has led to calls for greater investment in vaccines for other rare but potentially dangerous outbreak diseases such as Marburg, Sars and Chikungunya.