since finding out if they actually stop a person from getting a disease would be 'unethical'.)
First of all, T cells are involved in the adaptive immune system, not innate immune system. Secondly, clinical trials are when vaccines are tested on humans, and those are not forced. People consent to participate. Whatever response is seen on test animals can be tested to see if the response is mimicked in humans.
the unethical misread bit tvbcof talks about is that although people volunteer to have a vaccine. doctors then later do not force the actual virus on people by making them lick the faces of sick people or perform mouth to mouth exposure... as that is unethical
however many trial use candidate demographs where their natural exposure from their home/work life puts then at a high chance of getting exposed to the virus later without any forced exposure
this group is usually doctors followed by teachers.
the UK,US and even russia are doing their phase 2 and 3 trials on this group. because its not jsut about side effects or longevity of the vaccine. but also exposure NATURALLY to other people in their lives that can pass on the virus.
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the other part of the study where they said that antibody rates went up for the 3 months after symptom onset. is a sign that the person that recovered. was getting persistant exposure to people around them so the antibodies were fighting off the next infection before any symptoms appeared
doctors are doing periodic blood sampling of those taking the vaccine because seeing levelling out of antibody production means there is no current threat. but seeing a rise later means it has detected a threat. and not having symptoms but having this raised antibody count long after the first recover is a sign of re-infection assymptomatically. which is a good sign it done its job
what they dont want to see is where people that were sick months before get sick again to the same extent they did the first time