And thus I think it is time to put the two words together to make the most epic blog post title possible and write about….
Prior to last year Ebola was considered nasty but rare and reasonably easy to control. Only when it unexpectedly cropped up thousands of miles from where it was known to hang out, then made its way into a country with no health infrastructure and a culture that placed huge value on close care for recently deceased people did it kick off. So, with the exception of some military research, there was little effort put on developing prevention, and no vaccines were available. Because no vaccines (and therefore no vaccine photos) are available, I am just putting random photos from Sierra Leone into this post for you to enjoy.
The Ebola virus has very little of its surface covered with glycoproteins, most of it is lipids and sugars. Glycoproteins are relatively fixed structures whereas lipids and sugars are variable in shape and constantly changing, so it’s the glycoproteins that tend to get put in the vaccines. The trouble is, if there is little glycoprotein to bind to it is hard to create antibodies that will be effective. Of course being so dangerous Ebola is difficult to work with (I can attest to that!) so only the most specialized labs can work on it. There are several strains of Ebola virus and other similar haemorrhagic fevers, and ideally a vaccine would cover most if not all of them. Finally, of course, its rarity prior to last year made any clinical tests extremely difficult to perform: you could measure antibody levels, but could not know if that translated into a real clinical effect.
Then last year came along and changed everything. All of a sudden political will met clinical need and many labs around the world worked very hard to create a vaccine. That brought its own questions: years worth of work were being crammed into months, and processes needed shortening. Experts had to decide what if any of the safeguards and licensing regulations that would normally take many years to get through in development of a new drug could be shortened. There was great debate about whether or not to allow relatively untested interventions and who to test those interventions on, and whatever your opinion there is no doubt that Ebola, with its huge mortality, is a special case.
Now several vaccines have completed phase 1 and 2 trials (small trials on healthy people to assess safety and dosing) and are moving to phase 3 trials soon. In phase 2 studies both achieved reasonable (but not amazing) antibody responses with little in the way of side effects (1 vaccine caused joint pain, but this was temporary and worse with higher doses that didn’t change the effect of the vaccine). There was talk a few weeks ago of one of these companies looking for volunteers for their phase 3 trial in Sierra Leone. They were looking to test it on health care workers as we are at higher risk of the illness and thus easier to detect a vaccine effect in. These trials are scheduled to start in the next couple of months.
Ebola is an illness that has a very high mortality and also affects small pockets of people – families and small communities – due to its mechanism of spread. A vaccine would be a wonderful weapon to have against the virus to help snuff out the last of these pockets. Of course, now the epidemic is subsiding it will be harder to detect vaccine effect in the phase 3 trials. (Watch this space on the case decline – due to increased efforts in detection numbers could well increase again before they decline properly.) But that, I think, is a very good problem to have.