Ebola outbreak goes from bad to worse

A dire situation, but perhaps a glimmer of hope is on the horizon

The news from central Africa over the past two weeks has been grim, and it is getting worse. On 15th May, the Democratic Republic of the Congo and Uganda jointly declared an outbreak of Ebola disease, and two days later the WHO declared it a public health emergency of international concern. It is the DRC’s 17th Ebola outbreak since the virus was first identified in 1976, and it has escalated with alarming speed. The background to the current outbreak was covered here previously.

Not now, Ebola

Here is an update on the current situation, why it is so terrible, and why this is not the beginning of a global pandemic.

The situation

The numbers are bad and moving daily. As of June 1st, the DRC and Uganda Ministries of Health report 321 confirmed cases in the DRC, including 48 confirmed deaths, with a further 116 suspected cases still under investigation. The great majority are in Ituri Province, where the outbreak began, but it has spread west into North and South Kivu. Uganda has 11 confirmed cases, including one death, several linked to travel from the DRC; cases have reached the capital, Kampala.

Two features make this particularly difficult. The first is that by the time the outbreak was formally declared, it already had hundreds of suspected cases. It’s like a fire that had been spreading for some time before anyone reached for the alarm.

The second is community resistance to the response. This is a recurring and tragic feature of Ebola outbreaks. There are a mix of reasons with related results.

Families, understandably, do not want their sick relatives taken away to isolation units from which many never return, and traditional burial practices involve washing and touching the body of the deceased. There have been reports of family members retrieving bodies from quarantine. This is an act of love that, with this disease, is one of the most dangerous things a person can do. It is a particular tragedy of Ebola that the people most likely to catch the disease are those caring for others who are dying of it; both as family members or healthcare workers.

Misinformation is rife, including conspiracy theories around organ harvesting, the government scamming for aid money, or even that the Ebola virus does not exist at all. Locals set fire to the Ebola quarantine unit at Rwampara General Hospital, with many patients escaping.

As if this is not difficult enough, much of the affected area is currently embroiled in a civil war. Conditions are almost unimaginably difficult for frontline workers providing aid and healthcare. Resistance to outbreak response was a defining problem of the West African epidemic a decade ago, and it is the reason community engagement matters as much as any medical intervention.

A quick warning on some of the graphs you may be seeing shared, including by serious commentators (or even frustratingly by the BMJ). Some charts circulating online show case numbers rising near-vertically over the past fortnight, which looks terrifying. But much of that rise reflects case ascertainment catching up with an outbreak that was already large, not the speed of new transmission. When an outbreak is declared late, the early part of any cumulative curve always looks explosive, because you are counting cases that accumulated over weeks and recording them all at once.

Tellingly, the DRC's figures were recently revised downward after authorities removed non-cases and reclassified others. The curve was partly an artefact of counting, not just of spread. The outbreak is serious enough without misreading the shape of the graph, and this only risks further mistrust in health communicators.

Why this is not the next pandemic

Ebola, for all its horror, is not suited to becoming a pandemic. The pathogens that cause pandemics share a particular profile: they transmit efficiently through the air, and crucially, they transmit before the infected person feels very unwell. That combination is what allows a virus to spread silently through a population faster than any response can contain it. It is what made Covid-19 impossible to contain.

Ebola is almost the opposite. It is not airborne. It spreads through direct contact with the bodily fluids of someone who is symptomatic, and people with Ebola become very symptomatic, very obviously, very quickly. Transmission is concentrated in the late symptomatic phase and, grimly, around death, which is why infections cluster so tightly around carers, healthcare workers, and funerals. A disease that mostly spreads from people who are visibly, severely ill is a disease you can, in principle, contain by isolating the ill and managing burials safely. This is hard, dangerous, resource-intensive work, but containable in a way that an airborne, pre-symptomatic virus simply is not.

This also means that the interventions people instinctively reach for after the last pandemic are largely beside the point. Community masking will not help here. The transmission route is wrong. This is a disease controlled by contact tracing, safe isolation, safe burial, and hopefully, vaccination.

It also makes some of the political responses hard to fathom. The US has declared it "cannot and will not allow" any Ebola cases onto American soil, and rather than repatriating exposed citizens (as it did during the 2014–16 West African outbreak) it has moved to house them in a quarantine facility at an air base in Kenya, a country with no Ebola cases of its own. The plan has been temporarily blocked by the Kenyan High Court pending a legal challenge from local civil society groups, who object to having infectious disease risk "externalised" onto Kenyan territory. Leaving aside the question of a government declining to bring its own citizens home, the epidemiology does not warrant this response. With a disease this hard to catch from someone who isn't visibly ill, sealing borders does little except discourage the transparency and cooperation that outbreak response depends on. Indeed, it makes it more likely that high risk individuals will seek to circumvent the very safety nets that are put in place to prevent imported cases. Some lessons are never learnt.

The vaccine story

Amongst all the very bad news about this outbreak, there is a cause for some optimism.

We already have a highly effective Ebola vaccine but for the wrong species. The rVSV-ZEBOV vaccine (Ervebo) was tested in the remarkable “Ebola ça Suffit” ring vaccination trial in Guinea in 2015, which used a design inspired by the strategy that eradicated smallpox: when a case is confirmed, you vaccinate their contacts and their contacts’ contacts; the “ring” around the case. The interim results showed 100% efficacy against Ebola disease from ten days after vaccination. It was a landmark, and ring vaccination has been a mainstay of outbreak response ever since.

The complication is that Ervebo protects against Zaire Ebolavirus. This outbreak is caused by Bundibugyo virus, a different species, and we do not have an off-the-shelf licensed vaccine for it.

What we do have is a platform. The Oxford Vaccine Group is producing a vaccine, ChAdOx1 BDBV, built on the same ChAdOx viral-vector technology that underpinned the Oxford/AstraZeneca Covid vaccine. It is currently in preclinical testing (the animal studies needed before it can be given to people) with manufacturing already running in parallel through Oxford and the Serum Institute of India.

I find this particularly encouraging, as I was involved in the deployment of the Covid vaccine. I can tell you from my own experience, that the speed at which a platform like this can move from genetic sequence to deliverable doses, when the will and infrastructure are there is astonishing. The ChAdOx platform was built precisely for this purpose. Swap in the genetic code for a new pathogen’s surface protein, and much of the manufacturing and safety groundwork is already done.

CEPI have now encouragingly added their backing to the project, alongside two other candidate vaccines for Bundibugyo virus; these include an mRNA vaccine, and a rVSV based vaccine (this is the same platform that the successful Zaire vaccine was built on). Separately, GAVI have also offered tens of millions of dollars in purchasing commitments to ensure vaccine makers know there will be a market if the vaccines are effective.

The “Ebola ça Suffit” trial gives us a proven model for testing a vaccine’s efficacy in the field, in the middle of a real outbreak. The pieces exist. The question is whether they can be assembled fast enough to matter for this outbreak, rather than the next one.

There are also plans in the work for rapid deployment of clinical trials for antiviral therapies, including monoclonal antibodies and the antiviral medicine “Remdesivir”, used during the Covid-19 pandemic. Finally, a post-exposure prophylactic antiviral, “Obeldesevir” (yes, this is related to Remdesivir), is also planned to enter trials in the region

These are predominantly aimed at treating patients who have contracted Ebola, or already been exposed but will not be impactful for stemming the spread of disease. This is why vaccination is key.

Undertaking these trials in a literal warzone alongside a population with high degrees of institutional mistrust will be a challenge, to say the least. Whilst they will come quickly, they won’t come quickly enough that they can be depended upon. Boots-on-the-ground public health measures are needed to stem the tide for the foreseeable future.

Summary

This is a serious and escalating outbreak, made worse by late detection and by community resistance to the response. These are the same human factors that have always made Ebola so hard to fight.

This is not the beginning of a pandemic. Ebola is not airborne, it spreads overwhelmingly from people who are visibly and severely ill, and it is therefore containable through isolation, safe burial, and ring vaccination. We have a proven vaccine for the wrong species and promising candidates for the right one in early development. The danger here is real and local; the risk to the wider world is low. Both things are true at once.