April 6, 2009 The Pump Handle 0Comment

by revere, cross-posted from Effect Measure

When an Ebola virus related lab accident in German occurred, special pathogens researchers girded themselves for bad news. Working with agents for which there is currently no treatment of vaccine requires high containment laboratories, often touted as being virtually fail safe. While engineering and procedural controls can be instituted to minimize accidents, the wild card is always the human element, so accidents in these laboratories happen. There has already been an Ebola related death in such circumstances, and when the German woman pricked her finger with a needle containing Ebola virus, there was fear of another. While there is no vaccine for Ebola currently in use, several are in development, and one was tried on an emergency basis. The incubation period is now past and the lab worker remains healthy. Was it the vaccine that saved her would she not have developed Ebola in any event? Helen Branswell (Canadian Press) takes it from there:

The makers of an experimental Ebola vaccine are hoping the blood of a German researcher exposed to Ebola virus will reveal whether use of the vaccine helped save her life.[snip]

But they hope to turn an unfortunate event into an opportunity. The unnamed woman, who has survived, was the first human to receive this experimental vaccine, made at the National Microbiology Laboratory in Winnipeg.

“I think we’ll learn some more about this vaccine and how it behaves in humans, that’s for sure,” says Dr. Frank Plummer, scientific director of the Winnipeg lab.

Plummer and Dr. David Butler-Jones, Canada’s chief public health officer, made the decision to let the woman’s doctors inject her with the Winnipeg vaccine, the only one of several experimental Ebola vaccines which has been shown to enhance chances of survival after exposure to the deadly virus. (Helen Branswell, Canadian Press)


Learning more about this vaccine is not a given. For starters, we don’t know if she was ever infected with Ebola virus. She developed a fever not long after she got the vaccine, but that was probably from the vaccine itself. Her blood well be examined to see if she developed antibodies to Ebola, showing she was indeed infected and whether she developed antibodies elicited by the vaccine, a live virus vaccine that combined Ebola protein combined with another virus (vesicular stomatitis virus). If she has antibodies linked both to the vaccine and the Ebola she was working with, that is the best outcome — evidence that the vaccine may have been effective. On the other hand, she may only have antibodies related to the virus. What would that mean?

It could mean she was never infected but the vaccine was successful in producing antibodies. But in that case there are still two possibilities. The first is that the antibodies produced by the vaccine are protective, although she didn’t need protecting because she wasn’t infective in the first place. Or that the vaccine produces antibodies but they wouldn’t have been effective in protecting had she been infected. Yet another possibility is that there were no antibodies for the virus because the vaccine was so effective it couldn’t replicate sufficiently to produce an antibody response on its own. We are stuck with the counterfactual possibility that can’t be tested: what would the outcome have been had she not been vaccinated?

What if there is no evidence of any kind of antibody? Looking on the bright side, we could say that it shows the vaccine is safe, since she is alive and healthy. But we wouldn’t know much about its ability to protect against Ebola, only that in one person the vaccine itself didn’t make the person sick, something we know for all the other cases, too. So it seems like this would be the least satisfactory outcome.

The Ebola lab accident is itself a political and public relations problem for labs like this. Under the Bush administration these high containment facilities were popping up like mushrooms after a (terror) reign with no planning as to how many we need or whether there was adequate trained staff to operate them (see some of our posts on this here). It turns out that the agents worked on in these labs tend not to be that risky for the public since, like Ebola, they aren’t very contagious (although they are often very deadly). The main at risk people are the lab workers, as in this case. Ironically, many of the really scary and contagious agents are worked on at lower levels (although still high) levels of containment. Bird flu (H5N1) is an example, which is used in BSL3 (enhanced) containment, a level down from where Ebola is used. But the word Ebola is more frightening than influenza, so accidents like this have to be contained in two ways: medically and via the public relations spin machine. I fully expect that at some point the mere existence of the experimental vaccine will be used as an argument for the value of these laboratories, whatever the outcome of this case. That side steps the question of how many such labs are needed, what they are doing, and who is doing oversight of their activities.

In the Bush years there was no more oversight of this stuff than there was of the banks and hedge funds. We’ll have to see if Obama does any better or whether he’ll continue to let the scientific foxes be in charge of the public hen house.

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