Health officials have warned that the second-deadliest outbreak of Ebola may spiral out of control unless attacks by armed groups on medical facilities and workers in the Democratic Republic of the Congo (DRC) stop.Speaking to reporters in Geneva on Wednesday, Oly Ilunga Kalenga, the DRC's health minister, said the government of his country was struggling to contain the spread of the virus amid a spike in violent attacks against doctors and hospitals that were dangerously delaying the emergency response."The real emergency we face right now is security," Kalenga said on the sidelines of the World Health Assembly, which is under way this week in the Swiss city."Each time there is an attack on a health facility or medical personnel, the response to the epidemic is put on hold and we lose precious time to stop the virus from spreading further".'Complex health emergency'Kalenga's comments highlighted growing concerns by the world's health authorities, who fear a new pandemic just three years after the last outbreak in West Africa killed more than 11 000 people between 2014 and 2016. "We are fighting one of the world's most dangerous viruses in one of the world's most dangerous areas," Tedros Adhanom Ghebreyesus, the director-general of the World Health Organisation (WHO), told health ministers on Monday."This outbreak is one of the most complex health emergencies any of us have ever faced."Unless we unite to end this outbreak, we run the very real risk that it will become more widespread, more expensive and more aggressive."Violence, mistrustIntercommunal violence has afflicted eastern DRC for decades, with a number of armed groups operating across a region that has historically been neglected by the central government in the capital, Kinshasa. The situation has worsened over the past years, creating hundreds of thousands of internally displaced people and almost a million refugees in neighbouring countries, according to the UN's refugee agency.In addition to violent attacks, medical workers' efforts to contain the spread of the disease have been hampered by widespread community distrust of health agencies and institutions. A recent study by the Lancet Infectious Diseases journal showed that more than 30 percent of respondents believed that the virus was fabricated for the financial gain of local elites or to cause further destabilisation.For his part, Kalenga dismissed the suggestion that the attacks may hide a political agenda."I think these are just spoilers in some of the provinces who want to see the government's response to the epidemic fail," he said. "I don't think there is a clear agenda behind these attacks but the security agencies are studying the situation".Vaccination campaignsSince the start of the outbreak in eastern DRC's North Kivu in August last year, at least 1,223 people have died out of 1,847 confirmed Ebola cases, Kalenga said. Thirty percent of those who died were children, according to WHO figures.The transmission remains most intense in seven hotspot areas: Katwa, Mabalako, Mandima, Butembo, Musienene, Kalunguta and Beni. Kalenga said, however, that the Congolese authorities had been successful in containing the epidemic from spreading further.Still, the growing number of assaults is discouraging people from reaching life-saving treatment and delaying the vaccinations campaigns, thus increasing the risk of transmission. In Butembo, vaccinations were taking place at the rate of 1,000 per day until an armed group killed a WHO doctor on April 19, bringing the vaccination campaign to a temporary stop.According to UN figures, more than 130 attacks on health facilities have taken place since the start of the outbreak. Thirty-eight people, including civilians and health workers, have died as a result of these assaults.The precarious security situation has forced Congolese to flee the country and heightened concerns about the possible cross-border spread of Ebola into Uganda, Zambia and Burundi.Meanwhile, the main focus of the DRC's authorities remains prevention through vaccination and awareness campaign run in accordance with local authorities and tribal leaders. Ten months into the outbreak, more than a 100,000 people have been vaccinated, Kalenga said.The vaccine has proven successful in 97% of the cases. Twenty-five per cent of those vaccinated were at a very high risk of contagion.The 2014–2016 outbreak in Guinea, Liberia and Sierra Leone involved both urban and rural areas. It was the deadliest and most complex Ebola outbreak since the virus was first discovered in 1976, ending with more than 28 600 cases and 11 325 deaths.