How to Make an Ebola Vaccine: 5 (Simplified) Steps

We’re only on step three.

Professor Adrian Hill, Director of the Jenner Institute, and Chief Investigator of the trials with the ebola vaccine called Chimp Adenovirus type 3 (ChAd3), holds up the vaccine before the first healthy UK volunteer receives their ebola vaccine.
National Journal
Oct. 29, 2014, 1 a.m.

Jo­nas Salk, in­vent­or of the polio vac­cine, was born 100 years ago this week, and the con­tri­bu­tions he made to sci­ence still save count­less lives. That’s be­cause the sci­entif­ic dogma be­hind his vac­cine still holds true: If you ex­pose a body to de­ac­tiv­ated, non­con­ta­gious ver­sion of a vir­us, when a live bug comes along, that body will be ready.

The same prin­ciple would ap­ply to an Ebola vac­cine. That is, if one was avail­able for the hu­man body. Ebola vac­cines ex­ist, but un­til now, they have only been tested in mon­keys.

Hu­man clin­ic­al tri­als for an Ebola vac­cine began only this year. The World Health Or­gan­iz­a­tion re­ports the data from these first tests will be avail­able in Decem­ber.

“We need to speed up that time point,” says Clive Gray, a pro­fess­or of im­mun­o­logy at the Uni­versity of Cape Town in South Africa. By Decem­ber, the ef­forts may be too little, too late. And res­ults from the first phase of tri­als don’t mean wide-scale pro­duc­tion. They mean more clin­ic­al tri­als. The time clock is grim and run­ning thin: The most pess­im­ist­ic scen­ari­os pre­dict as many as 1.4 mil­lion cases of the dis­ease by Janu­ary.

It’s not the sci­ence that has held an Ebola vac­cine back. In 2005, re­search­ers re­por­ted a vac­cine that was 100 per­cent ef­fect­ive in pro­tect­ing mon­keys from the ill­ness. That should have pro­moted a hu­man tri­al. But it didn’t.

“The cur­rent Ebola out­break is the same vir­al strain — the Zaire Ebola vir­us strain — as the very first out­break.”

Why? Simply and sadly, it was bad busi­ness for drug man­u­fac­tur­ers. Past out­breaks have been small and con­fined to poor coun­tries with fal­ter­ing pub­lic-health sys­tems. Now, with in­ter­na­tion­al at­ten­tion fo­cused on Ebola, an Ebola vac­cine will be­come a real­ity. WHO re­ports that clin­ic­al tri­als are un­der­way in three coun­tries and will soon com­mence in four oth­ers.

But the crux of the Ebola-vac­cine prob­lem is this: It takes time to take a vac­cine that’s ef­fect­ive in mon­keys and en­sure its safety and ef­fic­acy in hu­mans.  “As we ac­cel­er­ate in a mat­ter of weeks a pro­cess that typ­ic­ally takes years, we are en­sur­ing that safety re­mains the top pri­or­ity, with pro­duc­tion speed and ca­pa­city a close second,” Mar­ie-Paule Kieny, WHO as­sist­ant dir­ect­or-gen­er­al, said in a press re­lease.

So what does it take to bring a vac­cine from the lab to the field where it is des­per­ately needed? I asked Dr. Gray to lay out how it would work. To sim­pli­fy, it takes five steps. And we’re only on Step 3.

Step 1: Identi­fy the Tar­get

The first step in cre­at­ing a vac­cine is to study the struc­ture of the vir­us. Know­ing the struc­ture al­lows sci­ent­ists to mim­ic its struc­ture in a ser­um. Again, that’s the key to an ef­fect­ive vac­cine: to in­ject in­to some­body a sub­stance that looks like the vir­us, but is not the vir­us.

This pro­cess is a lot harder for some vir­uses than oth­ers. HIV and the flu, for in­stance, are con­stantly mutat­ing, cre­at­ing new forms that can fool the im­mune sys­tem. That’s why a new flu strain crops up every year. HIV is even more elu­sive — it can mutate and evade an im­mune re­sponse with­in one per­son’s body.

Thank­fully, Ebola isn’t like the flu or HIV. “The cur­rent Ebola out­break is the same vir­al strain — the Zaire Ebola vir­us strain — as the very first out­break,” Gray says. “And it hasn’t changed. Each per­son who be­comes in­fec­ted, gets in­fec­ted with the same vir­us.” That means one vac­cine can pro­tect all people from Ebola, without the need for yearly up­dates.

Step 2: Mim­ic the Tar­get

All the im­mune sys­tem needs to identi­fy a vir­us is the vir­us’s out­er pro­tein coat. The out­er pro­tein coat is the vir­us’s call­ing card. That’s what sci­ent­ists have re­cre­ated in the Ebola vac­cines now in tri­al. “They are tak­ing the ge­net­ic ma­ter­i­al from Ebola that codes for the pro­tein coat and they in­sert that ge­net­ic ma­ter­i­al in­to the skel­et­on of an­oth­er vir­us,” Gray says.

That skel­et­on vir­us won’t get a per­son sick, but will, in a sense, tell the im­mune sys­tem about the Ebola vir­us. The body will then start pro­du­cing the an­ti­bod­ies ne­ces­sary to con­tain Ebola.

Step 3: Test in An­im­als

The an­im­al tests en­sure that the vac­cine pro­vokes the in­ten­ded im­mune re­sponse against the Ebola vir­us. “The an­im­al test­ing has been done on these ex­ist­ing vac­cines,” Gray says. “That’s where the field is at now.”

Up un­til this point, The New York Times ex­plains, “the re­search may have cost a few mil­lion dol­lars, but tests in hu­mans and scal­ing up pro­duc­tion can cost hun­dreds of mil­lions, and bring­ing a new vac­cine all the way to mar­ket typ­ic­ally costs $1 bil­lion to $1.5 bil­lion.” And that’s why we’ve stalled at Step 3.

Step 4: Test in Hu­mans

That an­im­al-tested vac­cine would not give any hu­man Ebola, but that doesn’t mean it’s safe for hu­mans. Early-stage vac­cines can have dan­ger­ous side ef­fects.

In the very first clin­ic­al tri­als, re­search­ers “are put­ting these vac­cines in­to people to make sure they are safe, and also to see if the im­mune re­sponse in the people looks very sim­il­ar to the im­mune re­sponse in the mon­keys in the an­im­al stud­ies,” Gray says. Once it is de­term­ined to be safe and ef­fect­ive, the cor­rect dosage needs to be as­sessed. “If you give too much, maybe it would make the per­son feel sick, and if you give too little, it won’t be ef­fect­ive,” he says.

Re­search­ers will also con­sider the mode of in­jec­tion — should it be in­jec­ted in­to the muscle or just un­der the skin?

These clin­ic­al tri­als need to be con­duc­ted care­fully, and can of­ten take years to en­sure a vac­cine that is safe for mass con­sump­tion. “You can­not give people something that is un­safe,” Gray says.

Step 5: Pro­duce and Dis­perse

What does this step in­volve? “Fund­ing, simple as that,” Gray says. “If you give enough money, if you give enough dol­lars, it can be scaled up quickly.” Glaxo­S­mithK­line, the phar­ma­ceut­ic­al mega-gi­ant, has es­tim­ated it could pro­duce 1 mil­lion doses of a vac­cine a month by 2016. Two years might be light­en­ing fast when it comes to drug ap­provals, but when look­ing at the tra­ject­ory of the cur­rent Ebola out­break, two years may be an etern­ity.

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