CoVid19 and "challenge trials"

["Roger"]

The NY Times had a very long article on the year ahead that covered a very diverse set of topics. One that particularly interested me (I used to teach a course on biomedical ethics) was the possibility of using "challenge trials" to speed up the development of an effective vaccine.

Basically, a challenge trial is where a smaller group of volunteers is given an experimental vaccine, and then, purposely exposed to the disease in question. The advantages of this is that, since you know that the volunteers will have been exposed to the disease in question, you need fewer volunteers and don't have to wait as long for results.

Under normal conditions, challenge trials are only used (considered ethical) when there is a know cure for the disease in question. Thus, the volunteers face minimal risk. In the case of CoVid19, that would not be the case. So, the question becomes, given the dire nature of this crisis (not just the people contacting the disease, but the closing down of our economy and schools), should we allow volunteers to face the risk of contacting CoVid19.

One answer might be only young people with no other complicating conditions, but a concern, using a phrase from medical testing, "children are not small adults." What this phrase refers to is that, just because something works well with adults, you cannot assume that it will have the same efficacy with children. Dosages are a very big concern. Just because a child weighs half of an adult, does mean a half dosage will be just as safe for a child. Probably not.

Now, with CoVid19, for an effective vaccine, a challenge trial would have to include different ethnic groups, older citizens, females as well as males (I mention that because historically, drug manufactures use to exclude women from trials out of fear that they might be pregnant or would become pregnant during the trial) etc.

Perhaps the best way to think about this question would be to suppose a very close relative of yours (mother, husband, child, grandchild) was considering volunteering for a challenge trial, but was also very concerned about his or her own safety. Would you encourage that person to join the challenge trial or not?

 

[Brett]

The NY Times had a very long article on the year ahead that covered a very diverse set of topics. One that particularly interested me (I used to teach a course on biomedical ethics) was the possibility of using "challenge trials" to speed up the development of an effective vaccine.

Basically, a challenge trial is where a smaller group of volunteers is given an experimental vaccine, and then, purposely exposed to the disease in question. The advantages of this is that, since you know that the volunteers will have been exposed to the disease in question, you need fewer volunteers and don't have to wait as long for results.

Under normal conditions, challenge trials are only used (considered ethical) when there is a know cure for the disease in question. Thus, the volunteers face minimal risk. In the case of CoVid19, that would not be the case. So, the question becomes, given the dire nature of this crisis (not just the people contacting the disease, but the closing down of our economy and schools), should we allow volunteers to face the risk of contacting CoVid19.

One answer might be only young people with no other complicating conditions, but a concern, using a phrase from medical testing, "children are not small adults." What this phrase refers to is that, just because something works well with adults, you cannot assume that it will have the same efficacy with children. Dosages are a very big concern. Just because a child weighs half of an adult, does mean a half dosage will be just as safe for a child. Probably not.

Now, with CoVid19, for an effective vaccine, a challenge trial would have to include different ethnic groups, older citizens, females as well as males (I mention that because historically, drug manufactures use to exclude women from trials out of fear that they might be pregnant or would become pregnant during the trial) etc.

Perhaps the best way to think about this question would be to suppose a very close relative of yours (mother, husband, child, grandchild) was considering volunteering for a challenge trial, but was also very concerned about his or her own safety. Would you encourage that person to join the challenge trial or not?

good but I wouldn't want to be one of the volunteers

 

[TravelTime]

With other vaccines, have they done challenge trials? I was reading about the testing of vaccines and the timeline included challenge trials. This was not specific to Covid-19. I can understand that Covid-19 might be different and one where it could be unethical to do challenge trials. Just wondering what the normal testing process includes?

 

["Roger"]

Having been retired a number of years, I am not totally up on what vaccines are currently being tested by challenge trials. Influenza vaccines had been commonly tested this way. Historically, two noteworthy challenge trials, neither of which involved vaccines, were connected with yellow fever and ulcers.

In the first case, Walter Reed (think Walter Reed Hospital named in his honor) gained his notoriety for a series of experiments proving that yellow fever was caused by a single type of mosquito. In the most conclusive experiment, he had three rooms set up with volunteers in each room. One had bedding and other materials from people that had contracted yellow fever (which is how most people then thought that yellow fever was transmitted), a second had the mosquito in question, and the third nothing of note. Reed correctly said that he was given too much credit for recognizing that the mosquito in question was the cause but his tests were valuable.

A favorite challenge trial of mine was an Australian doctor who proved that ulcers were caused by a bacteria (h-pylori) and not stress. His theory was much in doubt. He got attention by downing a vial of h-pylori himself and contracting ulcers and then curing himself with an antibiotic. I like this because a doctor was willing to put himself at risk rather than signing up others. (I should mention in connection with Walter Reed, he did have the volunteers sign informed consent documents, something that had not been used before.)