says
ok, I will go back and make sure you have access.
Be...
Well-Known Member
There is a lot of news and to start with I need to some of the studies on the the duration of antibody responses (either in people who get the disease or people who get the vaccine). Bottom line, that tells very little about the duration of immunity. Antibody responses always go down at some point after an initial infection (or exposure to a vaccine) This is just how it works. What matters is what happens if the person is exposed to the virus a second time after this (this is called the secondary immune response). Because the immune system has "memory" usually the antibody response peaks again and a lot of cellular immune responses are triggered too. But not always, and in the case of SARS-CoV-2 we just don't know. There are reports of second infections in people but I'm not convinced, these may be people who never entirely eradicated the virus from their body. Time will tell, it could go either way (and it may be different in different people). Keep that in mind as we discuss vaccines.
The biggest news lately has been from (1) the Moderna RNA vaccine, and (2) the Oxford University/AstraZeneca vaccine, which uses an engineered chimpanzee adenovirus to deliver SARS-Cov-2 proteins into human cells to evoke an immune response (3) The CanSino Biologics vaccine from China, which uses an engineered human adenovirus. All three have evoked very strong immune responses based on being able to increase blood antibodies that neutralize SARS-CoV 2 proteins. So far they all seem safe. The Oxford vaccine was tested in healthy adults, all under age 55. In addition to inducing production of neutralizing antibodies, it also induced cellular immune responses, which is pretty interesting and important. A much stronger response appeared in a subset of patients who received a second booster shot. The CanSino Biologics also reported both antibodies and cellular immune responses. At first glance the responses to that vaccine seemed a bit weaker but it really is hard to compare directly since things were not evaluated the same way, and they didn't report responses to a booster injection. It is possible that some humans have antibodies against the human adenovirus vector, which can cause mild colds, and which could conceivably reduce effectiveness of that vaccine. This has also been published in the Lancet.
Finally I should mention that Pfizer/BioNTech have released results of a much smaller Phase 2 trial of their own RNA vaccines, actually two of them (similar to the Moderna one in principle). They have two additional ones in development. There vaccines required a second booster and resulted in strong antibody and T-cell responses (they say) but nothing published so far. If what they say is true, their responses are a bit better than the Moderna one.
So what do we know and not know? Well these are all Phase 1/2 trials of various sizes, which I explained earlier on this thread. We don't know if any of these will actually protect someone from getting Covid-19. That can only be ascertained from Phase 3 trials, which by their nature take a lot longer. But those will now proceed.
However there is reason to be cautiously optimistic. For the mean time, really try your best to not catch this virus!!!!
The biggest news lately has been from (1) the Moderna RNA vaccine, and (2) the Oxford University/AstraZeneca vaccine, which uses an engineered chimpanzee adenovirus to deliver SARS-Cov-2 proteins into human cells to evoke an immune response (3) The CanSino Biologics vaccine from China, which uses an engineered human adenovirus. All three have evoked very strong immune responses based on being able to increase blood antibodies that neutralize SARS-CoV 2 proteins. So far they all seem safe. The Oxford vaccine was tested in healthy adults, all under age 55. In addition to inducing production of neutralizing antibodies, it also induced cellular immune responses, which is pretty interesting and important. A much stronger response appeared in a subset of patients who received a second booster shot. The CanSino Biologics also reported both antibodies and cellular immune responses. At first glance the responses to that vaccine seemed a bit weaker but it really is hard to compare directly since things were not evaluated the same way, and they didn't report responses to a booster injection. It is possible that some humans have antibodies against the human adenovirus vector, which can cause mild colds, and which could conceivably reduce effectiveness of that vaccine. This has also been published in the Lancet.
Finally I should mention that Pfizer/BioNTech have released results of a much smaller Phase 2 trial of their own RNA vaccines, actually two of them (similar to the Moderna one in principle). They have two additional ones in development. There vaccines required a second booster and resulted in strong antibody and T-cell responses (they say) but nothing published so far. If what they say is true, their responses are a bit better than the Moderna one.
So what do we know and not know? Well these are all Phase 1/2 trials of various sizes, which I explained earlier on this thread. We don't know if any of these will actually protect someone from getting Covid-19. That can only be ascertained from Phase 3 trials, which by their nature take a lot longer. But those will now proceed.
However there is reason to be cautiously optimistic. For the mean time, really try your best to not catch this virus!!!!