7 ms·

Yes, you're correct. There are 3 major phases in clinically testing a drug's safety and efficacy before it's brought to market, and it seems like they're close

by reason 16y ago

Yes, you're correct. There are 3 major phases in clinically testing a drug's safety and efficacy before it's brought to market, and it seems like they're close to starting the first one. For all those interested in the 3 phases, here they are: Phase 1: Small number of healthy volunteers to assess drug safety, toxicity, and pharmacokinetics. Phase 2: Small number of patients with the disease of interest to test drug efficacy. Phase 3: Large number of patients with the disease of interest to test effects of new treatment in comparison to those of existing treatments. This is where you see double-blind studies, etc. Personally, this isn't terribly noteworthy. They've merely devised a new theory that's shown to be effective using animal models, and are still quite a ways away from seeing if similar results will occur with human testing. Of course, I do hope they see good results.

patrickaljord 16y ago
> Phase 2: Small number of patients with the disease of interest to test drug efficacy. > Phase 3: Large number of patients with the disease of interest to test effects of new treatment in comparison to those of existing treatments. I'm not sure phase 2 and 3 make sense for a vaccine though. Vaccines are only useful for healthy people. I guess the testing is done on healthy animals which are then transmitted the HIV virus, unless some people would accept to go through that kind of testing, not very likely but I'm no specialist so I may be wrong.
- evgen 16y ago
  For vaccines you test against a population and compare disease rates between the people who received the vaccine and those that did not. In situations like this I would guess that they will select a high-risk group and then compare infection rates over time between the two groups to see if the vaccine has any effect.
- deleted 16y ago
  [deleted]
- jessriedel 16y ago
  As explained elsewhere, you give the vaccine and a placebo to an at-risk. Than you follow up X years later to check infection rates. Everything's double blind, so there's nothing statistically different about the two populations other than the vaccine vs. placebo. http://news.ycombinator.com/item?id=2389732 http://news.ycombinator.com/item?id=2389732
  - electromagnetic 16y ago
    Super-sucks to be in the placebo group on this one if the vaccine really works. It reminds me of a study done in IIRC South Africa (although it's been a year or more since I heard of this so it could be anywhere in Africa really) where they circumcised a group of males to see the effect on HIV contraction and it was so great (due to HIV's severely limited lifetime outside the body compared to over viruses and bacteria's) that they ended up circumcising the control group. Hopefully if this study goes well then they'll do the same. I'd sense a massive lawsuit if scientists caught major wind of a guaranteed vaccine and sat on it for the sake of evidence for 5 years and let X-many people get HIV.
    - Vivtek 16y ago
      I'd sense a massive lawsuit if scientists caught major wind of a guaranteed vaccine and sat on it That's why you do this phase in poor countries. Duh. For instance, contraceptives were widely tested in Puerto Rico in the 50's before being put on the national market in the 60's. They weren't initially sold in Puerto Rico, though, because there wasn't enough money in it yet. [Caveat: I don't know this from personal experience - it's common knowledge in Puerto Rico, but then it's common knowledge here in Indiana that Barack Obama is a foreign-born Muslim, so ... take it all with a grain of salt.]
      - pdelgallego 16y ago
        It is well documented, this a good documentary about it [1] And it was not the worst case. The US government infected people intentionally with syphilis and gonorrhea in Guatemala during the 40's to research about STD [2], last week the U.S. goverment was sued over those syphilis tests [3]. [1] http://www.youtube.com/watch?v=Brj6RGuB-es&feature=related http://www.youtube.com/watch?v=Brj6RGuB-es&feature=relat... [2] http://www.msnbc.msn.com/id/39456324/ns/health-sexual_health/ http://www.msnbc.msn.com/id/39456324/ns/health-sexual_health... [3] http://www.cbc.ca/news/health/story/2011/03/14/syphilis-guatemala-obama-lawsuit.html http://www.cbc.ca/news/health/story/2011/03/14/syphilis-guat...
- allending 16y ago
  Don't know much about drugs and trials so I am speaking out of my ass but I'd assume if the numbers were large enough, you don't actually infect the patients. I would expect you could compare the natural rate of infection in the target group vs the control group after many years taking into account the historical/expected rate of infection in a random sampling of the population involved.
- loxs 16y ago
  This is not true. There is no biological reason why a vaccine wouldn't work on an infected individual. What you say is a myth, mostly as a result of most vaccines being about accute infections, like smallpox. In those cases, there is no real idea in administering a vaccine to a person who is already ill, because by the time the immune system is ready with its strong specific answer (which is a matter of days), the patient would be either dead or cured by "natural" response to the virus. There are already vaccines targeting (successfully) diseases with a long incubation period. Examples for this are tetanus and rabies. You get your vaccine after being bitten (by a rat for example), and you are OK.
  - chris_j 16y ago
    In the case of rabies treatment, if the patient has not received the rabies pre-exposure vaccination then they must receive a dose of immunoglobulin (antibodies against the rabies virus) in addition to the rabies vaccine. Without it, the patient would die before their immune system would be ready to fight the virus. Receiving the dose of immunoglobulin gives the immune system enough time to start producing its own antibodies. For this reason, travellers to countries where immunoglobulin may not be available are often advised to get the rabies pre-exposure vaccination before they go.

by reason 16y ago

patrickaljord 16y ago

> Phase 2: Small number of patients with the disease of interest to test drug efficacy. > Phase 3: Large number of patients with the disease of interest to test effects of new treatment in comparison to those of existing treatments. I'm not sure phase 2 and 3 make sense for a vaccine though. Vaccines are only useful for healthy people. I guess the testing is done on healthy animals which are then transmitted the HIV virus, unless some people would accept to go through that kind of testing, not very likely but I'm no specialist so I may be wrong.

evgen 16y ago
For vaccines you test against a population and compare disease rates between the people who received the vaccine and those that did not. In situations like this I would guess that they will select a high-risk group and then compare infection rates over time between the two groups to see if the vaccine has any effect.
deleted 16y ago
[deleted]
jessriedel 16y ago
As explained elsewhere, you give the vaccine and a placebo to an at-risk. Than you follow up X years later to check infection rates. Everything's double blind, so there's nothing statistically different about the two populations other than the vaccine vs. placebo. http://news.ycombinator.com/item?id=2389732 http://news.ycombinator.com/item?id=2389732
- electromagnetic 16y ago
  Super-sucks to be in the placebo group on this one if the vaccine really works. It reminds me of a study done in IIRC South Africa (although it's been a year or more since I heard of this so it could be anywhere in Africa really) where they circumcised a group of males to see the effect on HIV contraction and it was so great (due to HIV's severely limited lifetime outside the body compared to over viruses and bacteria's) that they ended up circumcising the control group. Hopefully if this study goes well then they'll do the same. I'd sense a massive lawsuit if scientists caught major wind of a guaranteed vaccine and sat on it for the sake of evidence for 5 years and let X-many people get HIV.
  - Vivtek 16y ago
    I'd sense a massive lawsuit if scientists caught major wind of a guaranteed vaccine and sat on it That's why you do this phase in poor countries. Duh. For instance, contraceptives were widely tested in Puerto Rico in the 50's before being put on the national market in the 60's. They weren't initially sold in Puerto Rico, though, because there wasn't enough money in it yet. [Caveat: I don't know this from personal experience - it's common knowledge in Puerto Rico, but then it's common knowledge here in Indiana that Barack Obama is a foreign-born Muslim, so ... take it all with a grain of salt.]
    - pdelgallego 16y ago
      It is well documented, this a good documentary about it [1] And it was not the worst case. The US government infected people intentionally with syphilis and gonorrhea in Guatemala during the 40's to research about STD [2], last week the U.S. goverment was sued over those syphilis tests [3]. [1] http://www.youtube.com/watch?v=Brj6RGuB-es&feature=related http://www.youtube.com/watch?v=Brj6RGuB-es&feature=relat... [2] http://www.msnbc.msn.com/id/39456324/ns/health-sexual_health/ http://www.msnbc.msn.com/id/39456324/ns/health-sexual_health... [3] http://www.cbc.ca/news/health/story/2011/03/14/syphilis-guatemala-obama-lawsuit.html http://www.cbc.ca/news/health/story/2011/03/14/syphilis-guat...
allending 16y ago
Don't know much about drugs and trials so I am speaking out of my ass but I'd assume if the numbers were large enough, you don't actually infect the patients. I would expect you could compare the natural rate of infection in the target group vs the control group after many years taking into account the historical/expected rate of infection in a random sampling of the population involved.
loxs 16y ago
This is not true. There is no biological reason why a vaccine wouldn't work on an infected individual. What you say is a myth, mostly as a result of most vaccines being about accute infections, like smallpox. In those cases, there is no real idea in administering a vaccine to a person who is already ill, because by the time the immune system is ready with its strong specific answer (which is a matter of days), the patient would be either dead or cured by "natural" response to the virus. There are already vaccines targeting (successfully) diseases with a long incubation period. Examples for this are tetanus and rabies. You get your vaccine after being bitten (by a rat for example), and you are OK.
- chris_j 16y ago
  In the case of rabies treatment, if the patient has not received the rabies pre-exposure vaccination then they must receive a dose of immunoglobulin (antibodies against the rabies virus) in addition to the rabies vaccine. Without it, the patient would die before their immune system would be ready to fight the virus. Receiving the dose of immunoglobulin gives the immune system enough time to start producing its own antibodies. For this reason, travellers to countries where immunoglobulin may not be available are often advised to get the rabies pre-exposure vaccination before they go.